Year	Percent
1990	25.81947
1991	22.90761
1992	54.34522
1993	46.7501
1994	38.19437
1995	33.01121
1996	28.18024
1997	37.31219
1998	41.2065
1999	42.17177
2000	32.94684
2001	29.19851
2002	26.30124
2003	27.65637
2004	30.70417
2005	34.8076
2006	37.79148
2007	44.11688
2008	43.22447
2009	32.80554
2010	39.78975
2011	47.12443
2012	45.37447
2013	43.39647
2014	47.66286
2015	48.80034
2016	49.9727
2017	55.11288