Year	Percent
1991	33.908
1992	33.467
1993	33.304
1994	33.032
1995	31.372
1996	33.761
1997	33.354
1998	33.729
1999	33.729
2000	35.44
2001	34.548
2002	35.106
2003	35.02
2004	36.048
2005	35.623
2006	35.242
2007	35.287
2008	34.148
2009	34.345
2010	34.333
2011	34.464
2012	31.612
2013	30.992
2014	31.047
2015	31.013
2016	31.209
2017	31.766
2018	31.781
2019	31.794
2020	31.807
2021	31.836
2022	31.859