Year	Percent
1991	28.326
1992	29.374
1993	29.719
1994	29.573
1995	33.281
1996	35.324
1997	35.004
1998	33.304
1999	30.499
2000	28.341
2001	28.217
2002	29.551
2003	28.388
2004	30.758
2005	29.773
2006	28.979
2007	32.702
2008	34.559
2009	32.888
2010	28.445
2011	24.194
2012	20.294
2013	17.424
2014	21.156
2015	22.171
2016	28.578
2017	30.087
2018	32.133
2019	32.614
2020	32.255
2021	31.649
2022	30.749