Year	Percent
1976	70.34118
1977	28.4148
1978	59.26475
1979	24.86264
1980	19.82492
1981	25.60208
1982	26.49479
1983	29.94948
1984	33.20791
1985	40.53507
1986	47.99291
1987	46.01775
1988	41.64768
1989	32.11682
1990	28.57418
1991	30.89847
1992	29.83659
1993	21.72732
1994	18.72223
1995	18.92428
1996	19.03146
1997	17.79188
1998	13.90839
1999	16.64807
2000	18.76743
2001	20.90733
2002	24.80978
2003	22.51331
2004	20.6091
2005	22.52551
2006	16.18298
2007	23.56518
2008	19.54195
2009	34.95161
2010	28.04765
2011	36.67365
2012	37.39522
2013	26.42451
2014	33.17437
2015	87.96321
2016	40.40251