Year	Percent
1991	35.37293
1992	35.28948
1993	34.88491
1994	33.80706
1995	32.39097
1996	30.28304
1997	28.72499
1998	27.32501
1999	26.21356
2000	25.2499
2001	24.45153
2002	23.46421
2003	22.71051
2004	22.10647
2005	21.30974
2006	20.54513
2007	19.81873
2008	20.57951
2009	21.23215
2010	19.69918
2011	19.61312
2012	20.55814
2013	18.86158
2014	17.07907
2015	17.5155
2016	17.95728
2017	16.8242
2018	15.72489
2019	18.01657