Year	Percent
1986	49.6453
1987	49.5925
1988	48.3052
1989	42.58
1990	39.2654
1991	37.1258
1992	39.6536
1993	46.4799
1994	49.5502
1995	48.2283
1996	48.1826
1997	45.6653
1998	43.0071
1999	36.8221
2000	32.0787
2001	26.3409
2002	27.6651
2003	26.4207
2004	26.3908
2005	23.3787
2006	21.5022
2007	21.7118
2008	25.5202
2009	36.1159
2010	39.6069
2011	43.9861
2012	51.4391
2013	54.62
2014	52.9327
2015	47.9703
2016	44.8987
2017	37.4171