Year	Percent
1991	29.677
1992	30.78
1993	30.567
1994	31.193
1995	31.789
1996	32.24
1997	32.533
1998	33.182
1999	33.398
2000	33.834
2001	33.495
2002	34.343
2003	35.263
2004	35.794
2005	36.09
2006	37.155
2007	37.51
2008	38.156
2009	38.291
2010	37.422
2011	34.961
2012	32.191
2013	30.675
2014	31.296
2015	32.325
2016	32.828
2017	33.617
2018	33.637
2019	34.375
2020	34.613
2021	34.755
2022	34.748