Year	Percent
1990	39.22237
1991	41.20509
1992	54.59638
1993	75.98834
1994	30.63006
1995	41.51002
1996	55.54766
1997	53.02437
1998	54.53126
1999	41.87764
2000	38.37809
2001	37.31793
2002	50.04893
2003	65.55051
2004	72.71588
2005	52.89701
2006	38.75945
2007	28.5137
2008	23.46676
2009	23.1083
2010	20.68127
2011	24.08106
2012	25.28857
2013	26.65103
2014	26.2056
2015	34.80673
2016	43.64967
2017	41.97542