Year	Percent
1991	30.068
1992	29.343
1993	28.623
1994	28.414
1995	28.16
1996	28.446
1997	28.522
1998	28.843
1999	29.492
2000	30.178
2001	31.321
2002	31.945
2003	32.594
2004	34.338
2005	34.055
2006	34.638
2007	34.784
2008	35.128
2009	34.395
2010	34.157
2011	34.312
2012	34.528
2013	33.929
2014	33.961
2015	34.05
2016	34.569
2017	34.629
2018	34.822
2019	34.807
2020	34.706
2021	34.586
2022	34.454