Year	Percent
1991	26.34341
1992	26.44868
1993	26.60818
1994	26.62017
1995	26.49265
1996	26.31451
1997	26.06752
1998	25.69931
1999	25.15457
2000	24.58876
2001	24.39968
2002	23.92001
2003	22.04008
2004	21.40482
2005	20.80181
2006	20.12422
2007	18.2499
2008	18.25036
2009	18.53052
2010	18.62055
2011	18.74057
2012	17.31164
2013	18.73572
2014	18.46425
2015	17.86505
2016	16.62717
2017	16.24402
2018	15.72178
2019	13.89816