Year	Percent
1991	33.02125
1992	33.62002
1993	33.78901
1994	34.28466
1995	34.49119
1996	34.70652
1997	34.65828
1998	34.5776
1999	34.54239
2000	34.26192
2001	34.35259
2002	34.33679
2003	33.99688
2004	33.60963
2005	32.87827
2006	32.37222
2007	31.74077
2008	30.95073
2009	30.22087
2010	29.40921
2011	28.39875
2012	27.47191
2013	26.50691
2014	25.49017
2015	24.5713
2016	23.67024
2017	22.73159
2018	21.74418
2019	20.72863