Year	Percent
1975	8.47153
1976	13.46826
1977	19.09279
1978	30.9195
1979	35.83665
1980	44.20906
1981	51.04644
1982	58.43904
1983	52.88432
1984	35.88388
1985	45.22395
1986	50.9952
1987	42.42118
1988	32.36135
1989	40.72985
1990	28.41271
1991	34.65236
1992	52.47344
1993	46.10594
1994	46.77025
1995	48.11028
1996	40.44358
1997	39.09659
1998	34.18497
1999	35.11409
2000	29.72155
2001	27.03387
2002	34.10876
2003	33.83223
2004	19.99231
2005	15.81294
2006	16.88656
2007	16.1511
2008	13.30223
2009	13.67276
2010	11.82792
2011	9.86442
2012	10.91953
2013	15.31761
2014	12.96599
2015	10.50228
2016	10.87359