50 home runs: percent at home. Jimmie Foxx tops. Brady Anderson bottom.

HR≥50 for season(s) sorted by greatest percentage of total Home Runs:

Rk	I	Player	Split	Year	G	HR	HRtot	%	GS	PA	AB	R	H	2B	3B	RBI	SB	CS	BB	SO	BA	OBP	SLG	OPS	TB	GDP	HBP	SH	SF	IBB	ROE	BAbip	tOPS+	sOPS+
1		Jimmie Foxx	Home	1938	74	35	50	70.0	74	334	274	83	111	21	3	104	2	1	60	33	.405	.512	.887	1.399	243		0	0	0			.369	137	264
2		Hank Greenberg	Home	1938	79	39	58	67.2	79	343	277	77	97	9	1	92	5	2	63	43	.350	.471	.812	1.283	225		0	3	0			.297	126	234
3		Jose Bautista	Home	2010	78	33	54	61.1	78	323	262	65	74	16	2	69	3	1	55	42	.282	.412	.737	1.148	193	5	4	0	2	0	4	.217	128	200
4		Alex Rodriguez	Home	2002	81	34	57	59.6	81	360	313	74	101	14	1	82	5	3	38	62	.323	.403	.700	1.102	219	8	6	0	3	6	4	.305	115	184
5		Hack Wilson	Home	1930	78	33	56	58.9	78	365	289	77	112	13	3	116	2	0	65	33	.388	.501	.796	1.297	230	0	1	10	0		0	.354	120	214
6		Jim Thome	Home	2002	77	30	52	57.7	76	312	246	60	86	12	1	72	0	1	63	72	.350	.481	.772	1.253	190	2	1	0	2	10	3	.384	122	224
7		Mark McGwire	Home	1999	76	37	65	56.9	76	335	260	64	74	12	1	89	0	0	70	64	.285	.436	.765	1.201	199	7	2	0	3	13	2	.228	113	200
8		Johnny Mize	Home	1947	76	29	51	56.9	76	319	285	64	90	13	0	78	0	0	33	16	.316	.389	.667	1.055	190	2	1	0	0	2	4	.254	110	187
9		Ralph Kiner	Home	1947	77	28	51	54.9	77	334	278	58	88	10	3	67	0	1	56	40	.317	.431	.676	1.107	188	4	0	0	0	5	2	.286	109	202
10		Mark McGwire	Home	1998	81	38	70	54.3	79	364	263	72	83	10	0	80	0	0	94	83	.316	.497	.787	1.284	207	3	4	0	3	20	1	.310	110	229
11		Babe Ruth	Home	1921	78	32	59	54.2	77	339	256	94	103	24	7	80	11	7	80	34	.402	.545	.926	1.470	237		0	3	0			.374	116	276
12		Prince Fielder	Home	2007	80	27	50	54.0	78	337	276	53	83	20	0	71	2	1	51	55	.301	.421	.667	1.088	184	5	8	0	2	10	0	.286	114	178
13		Babe Ruth	Home	1920	66	29	54	53.7	65	272	203	77	81	21	6	70	7	8	63	38	.399	.545	.990	1.535	201		2	4	0			.382	119	317
14		Babe Ruth	Home	1928	77	29	54	53.7	77	328	260	76	86	8	4	70	2	4	61	47	.331	.461	.727	1.188	189		2	5	0			.310	102	210
15		Ralph Kiner	Home	1949	75	29	54	53.7	75	321	265	56	86	14	3	67	2	0	55	27	.325	.442	.728	1.171	193	5	1	0	0	3	1	.273	113	208
16		Ken Griffey	Home	1998	81	30	56	53.6	81	361	315	61	88	19	1	79	6	3	40	58	.279	.366	.632	.997	199	6	4	0	2	6	3	.253	104	154
17		Jimmie Foxx	Home	1932	77	31	58	53.4	77	355	283	87	110	21	4	94	2	3	72	47	.389	.513	.820	1.332	232		0	0	0			.385	119	245
18		Sammy Sosa	Home	2001	79	34	64	53.1	79	346	281	73	94	13	3	85	0	2	54	76	.335	.431	.765	1.196	215	2	1	0	10	19	4	.331	102	205
19		Sammy Sosa	Home	1998	78	35	66	53.0	78	347	310	64	93	11	0	77	9	5	34	79	.300	.366	.674	1.040	209	9	0	0	3	5	4	.291	101	164
20		Chris Davis	Home	2013	80	28	53	52.8	80	326	280	54	86	17	0	66	2	1	35	91	.307	.390	.668	1.057	187	1	6	0	5	5	2	.349	111	187
21		Sammy Sosa	Home	1999	81	33	63	52.4	81	355	308	62	100	15	1	71	3	4	44	76	.325	.406	.701	1.107	216	9	0	0	3	5	0	.332	121	177
22		Mickey Mantle	Home	1956	77	27	52	51.9	75	326	268	66	99	14	3	67	4	1	54	45	.369	.472	.746	1.219	200	0	1	0	3	2	2	.362	108	222
23		Mark McGwire	Home	1997	72	30	58	51.7	70	304	248	44	78	18	0	60	2	0	52	64	.315	.438	.750	1.188	186	5	3	0	1	8	2	.310	127	202
24		Barry Bonds	Home	2001	75	37	73	50.7	72	310	224	61	75	19	0	71	6	1	80	46	.335	.516	.915	1.431	205	2	5	0	1	17	0	.268	106	264
25		Ryan Howard	Home	2006	79	29	58	50.0	78	341	282	52	87	9	1	75	0	0	52	85	.309	.422	.656	1.078	185	5	5	0	2	18	3	.341	99	171
Rk	I	Player	Split	Year	G	HR	HRtot	%	GS	PA	AB	R	H	2B	3B	RBI	SB	CS	BB	SO	BA	OBP	SLG	OPS	TB	GDP	HBP	SH	SF	IBB	ROE	BAbip	tOPS+	sOPS+
26		Alex Rodriguez	Home	2001	82	26	52	50.0	82	362	313	71	113	19	1	65	13	3	36	59	.361	.439	.677	1.117	212	13	10	0	3	5	8	.377	119	187
27		Albert Belle	Home	1995	72	25	50	50.0	72	311	268	62	88	28	1	53	1	0	38	45	.328	.415	.720	1.135	193	13	3	0	2	3	1	.315	108	190
28		Roger Maris	Home	1961	79	30	61	49.2	78	325	280	59	80	6	0	73	0	0	39	31	.286	.372	.629	1.001	176	9	2	0	4	0	3	.224	101	165
29		Cecil Fielder	Home	1990	80	25	51	49.0	78	328	271	47	76	13	0	60	0	1	52	81	.280	.396	.605	1.002	164	4	2	0	3	7	5	.304	107	175
30		Ken Griffey	Home	1997	77	27	56	48.2	77	338	289	62	93	15	3	72	8	1	38	51	.322	.396	.675	1.071	195	4	3	0	8	12	2	.301	108	172
31		Alex Rodriguez	Home	2007	80	26	54	48.1	80	352	292	74	88	18	0	88	16	3	43	54	.301	.403	.630	1.034	184	11	11	0	6	1	1	.284	93	164
32		Babe Ruth	Home	1927	73	28	60	46.7	73	317	253	82	94	10	4	70	4	4	61	42	.372	.494	.775	1.268	196		0	3	0			.361	102	229
33		Mark McGwire	Home	1996	64	24	52	46.2	64	276	213	56	66	12	0	56	0	0	57	61	.310	.464	.704	1.168	150	7	5	0	1	9	0	.326	96	194
34		Willie Mays	Home	1965	78	24	52	46.2	73	311	272	63	87	13	1	48	4	2	37	29	.320	.400	.640	1.040	174	5	0	1	1	10	6	.286	100	197
35		Greg Vaughn	Home	1998	80	23	50	46.0	78	329	281	50	71	10	2	49	8	2	44	62	.253	.356	.548	.904	154	2	2	0	2	3	4	.242	90	132
36		Luis Gonzalez	Home	2001	81	26	57	45.6	81	355	301	60	103	16	3	66	1	1	42	43	.342	.434	.674	1.108	203	8	9	0	3	8	3	.328	99	184
37		Mickey Mantle	Home	1961	74	24	54	44.4	71	299	230	63	76	8	6	59	6	0	66	44	.330	.477	.730	1.207	168	3	0	1	2	6	5	.317	113	221
38		Sammy Sosa	Home	2000	77	22	50	44.0	77	340	291	44	89	15	1	59	2	3	46	82	.306	.400	.591	.991	172	5	1	0	2	14	1	.354	92	146
39		Willie Mays	Home	1955	79	22	51	43.1	79	338	298	59	98	13	8	55	10	0	37	23	.329	.405	.648	1.053	193	8	2	0	1	6	6	.299	100	178
40		Andruw Jones	Home	2005	79	21	51	41.2	78	331	281	48	74	10	2	67	3	2	36	53	.263	.360	.537	.897	151	9	9	0	5	6	3	.250	97	132
41		David Ortiz	Home	2006	74	22	54	40.7	73	333	267	52	80	15	2	72	1	0	61	59	.300	.426	.618	1.044	165	4	1	0	4	13	0	.305	100	164
42		George Foster	Home	1977	80	21	52	40.4	80	346	296	61	88	14	1	71	2	2	42	53	.297	.387	.564	.951	167	7	4	0	4	6	2	.296	91	153
43		Brady Anderson	Home	1996	79	19	50	38.0	78	361	300	59	84	23	3	46	12	3	40	58	.280	.385	.567	.952	170	6	14	3	4	0	2	.286	86	140

Provided by Baseball-Reference.com: View Play Index Tool Used
Generated 1/5/2015.

Brady Anderson 1999

50 home runs (HR) have been hit 43 times with some players doing it multiple times.  In 1938 Jimmie Foxx hit 70% of his 50 HR at home in Fenway Park in Boston.  This was two years before the Red Sox created bullpens in right center after the 1939 rookie season of Ted Williams, which brought in the fence.  Foxx was a right handed batter so the closer fence in right center may not have helped him but it did help lefty David Ortiz who broke the Red Sox record set by Foxx when Ortiz hit 54 HR in 2006.  However, Ortiz hit only 40.7% of  his HR in Fenway Park.  That's the third lowest 50 HR home percent.

Perhaps even more counterintuitive was the bottom guy: Brady Anderson who hit only 38% at home in what most people think is an easy HR park: Oriole Park at Camden Yards in Baltimore.

Another surprise was Willie Mays hitting only 43.1% in the Polo Grounds in New York in 1955.

27 of 43 hit at least 50% at home.  The 16 under 50% included:
Roger Maris 1961 61 49.2%
Babe Ruth 1927 60 46.7%
Sammy Sosa 2000 50 44.0%

Three players had at least 60% at home:
Foxx 1938 50 70.0%
Greenberg 1938 58 67.2
Bautista 2010 54 61.1

Foxx also hit 58 HR in 1932 playing for the Philadelphia Athletics before they moved to Kansas City before they moved to Oakland: 53.4% at home, number 17 of 43.

Ruth's positions:
11. 1921 59 54.2% Polo Grounds
13. 1920 54 53.7% Polo Grounds
14. 1928 54 53.7% Yankee Stadium
32. 1927 60 46.7% Yankee Stadium

60 HR:
Bonds 2001 73 50.7%
McGwire 1998 70 54.3%
Sosa 1998 66 53.0%
McGwire 1997 65 56.9%
Sosa 2001 64 53.1%
Sosa 1999 63 52.4%
Maris 1961 61 49.2%
Ruth 1927 60 46.7%

For multiple achievers:
Foxx 70.0% 53.4%
Griffey 53.6% 48.2%
Kiner 54.9% 53.7%
Mantle 51.9% 44.4%
Mays 46.2% 43.1%
McGwire 56.9% 54.3% 51.7% 46.2%
Rodriquez 59.6% 50.0% 48.1%
Ruth 54.2% 53.7% 53.7% 46.7%
Sosa 53.1% 53.0% 52.4% 44.0%

Most at home:
Greenberg 1938 39 of 58 67.2%
McGwire 1998 38 of 70 54.3%
Bonds 2001 37 of 70 50.7%
McGwire 1999 37 of 65 56.9%
Foxx 1938 35 of 50 70.0%

Sosa 1998 35 of 66 53.0%