Year	Percent
1975	15.27193
1976	18.10206
1977	15.61459
1978	15.33163
1979	12.28762
1980	11.33858
1981	12.70984
1982	15.4663
1983	18.31933
1984	20.64482
1985	25.44891
1986	35.58605
1987	33.36129
1988	31.45393
1989	31.50008
1990	32.95595
1991	32.02935
1992	28.7074
1993	28.83788
1994	32.27374
1995	33.25994
1996	27.61581
1997	26.30119
1998	24.77348
1999	18.6267
2000	17.08105
2001	17.9276
2002	20.92475
2003	29.1805
2004	14.50444
2005	14.93023
2006	8.63524
2007	15.59102
2008	9.65799
2009	6.01841
2010	6.81923
2011	6.41387
2012	6.70266
2013	8.0743
2014	18.51532
2015	11.22499
2016	17.30017