Year	Percent
1983	30.0629
1984	31.8471
1985	31.9784
1986	34.2082
1987	33.8032
1988	35.9977
1989	34.0006
1990	32.5908
1991	33.5166
1992	34.1687
1993	36.0374
1994	36.9339
1995	37.7013
1996	41.2929
1997	40.5755
1998	39.4391
1999	41.1577
2000	38.0324
2001	36.1208
2002	34.4526
2003	34.859
2004	35.0098
2005	34.193
2006	34.2459
2007	31.7016
2008	28.3472
2009	33.2824
2010	40.3097
2011	51.5603
2012	63.0539
2013	63.8393
2014	58.1103
2015	54.9957
2016	50.7184
2017	48.2048