plunks under roofs

Wednesday, DM asked about plunk rates for domes versus open air ballparks. So:

During the 1988 through 2005 seasons there were 32,328 major league games played in good old fashioned ballparks without roofs over them, 5,186 games played under fixed dome, and 2,859 played under retractable roofs. Ideally, the retractable roof games would be split between open air and dome depending on whether the roof is open, but sources for such information are lacking, particularly prior to 2003. So, during that span, batters in open air parks have been hit once per 131.86 times per plate appearance, batters in fixed domes have been hit 115.18 times per plate appearance and batters playing in retractable roof parks have been hit once per 104.75.
Craig Biggio's plunk rates are one plunk per 38.08 plate appearances under retractable roofs, 1 per 41.97 PAs in domes and one HBP per 42.89 PAs out where there's no protection from falling space debris.
Since 2001, when the most recent of the retractable roof parks opened, regular dome have had the most frequent HBPs with one every 93.07 plate appearances. Retractable roof parks have had 1 plunk per 99.44 plate appearances since then, and open air parks have had 1 per 104.24. But, the league is now down to only 2 fixed roof domes after the decline and fall of baseball in Montreal, and one of them, Tropicana Field, houses one of the top plunking teams in the league over those years. With Minnesota finally planning on building a new outdoor ballpark, the Tropicana Field will be the last trace of that fabulous future in which man will conquer nature by playing baseball indoors on a rug. (Although, Minnesota is not planning on building a retractable roof, so someone there will probably decide that instead of canceling games due to snow, they'll just go play inside at the dome.)

Here are the year by year plunk rates for open air parks, retractable roofs, and fixed domes, including number of games:

	Open air parks			Retractable roof parks			Domes
Year	G	HBPs	PA/HBP	G	HBPs	PA/HBP	G	HBPs	PA/HBP
2005	1945	1431	104.3	324	244	101.06	162	122	101.31
2004	1884	1432	102.24	324	224	112.08	220	194	87.64
2003	1885	1378	105.28	324	264	95.37	221	207	83.02
2002	1859	1326	107.6	324	235	106.5	243	185	102.13
2001	1862	1405	102.02	324	290	86.27	243	195	95.39
2000	1942	1218	124.93	243	201	94.7	244	154	123.64
1999	1902	1222	121.66	162	113	111.27	364	244	116.52
1998	1865	1193	120.98	162	107	116.41	405	287	109.65
1997	1861	1142	126.46	81	56	109.09	324	251	99.53
1996	1861	1041	139.69	81	61	104.26	325	302	84.32
1995	1656	951	135	72	59	98.05	289	209	107.78
1994	1327	709	145.72	59	39	116.1	214	128	129.94
1993	1864	954	150.29	81	43	147.07	324	203	122.4
1992	1701	725	178.7	81	51	119.78	324	204	121.82
1991	1712	718	182.06	81	60	103.2	311	127	187.56
1990	1700	670	193.41	81	34	182.38	324	157	156.13
1989	1726	629	207.94	55	27	153.63	325	145	172.93
1988	1776	757	178.09	0	0	0	324	24549	152.48