Year	Percent
1991	36.273
1992	37.135
1993	36.706
1994	36.291
1995	35.85
1996	35.422
1997	35.417
1998	35.09
1999	34.9
2000	35.147
2001	35.119
2002	34.146
2003	34.523
2004	33.161
2005	31.452
2006	31.729
2007	32.125
2008	33.357
2009	33.001
2010	33.543
2011	33.171
2012	34.028
2013	33.739
2014	32.384
2015	31.107
2016	32.519
2017	32.196
2018	31.645
2019	31.147
2020	30.717
2021	30.355
2022	30.054