Year	Percent
1991	20.184
1992	18.15
1993	17.919
1994	19.214
1995	18.929
1996	19.31
1997	19.03
1998	18.277
1999	18.389
2000	18.74
2001	18.18
2002	17.37
2003	17.022
2004	16.872
2005	16.95
2006	16.866
2007	17.35
2008	17.729
2009	20.648
2010	24.626
2011	26.808
2012	30.95
2013	31.531
2014	32.127
2015	32.849
2016	33.041
2017	33.041
2018	33.369
2019	33.82
2020	34.337
2021	34.966
2022	35.564