Year	Percent
1979	66.0685
1980	45.78645
1981	47.83595
1982	52.53548
1983	46.80097
1984	46.59242
1985	45.24816
1986	45.75539
1987	34.17633
1988	38.91058
1989	34.22661
1990	21.76717
1991	24.63232
1992	35.65209
1993	37.68693
1994	27.04372
1995	39.22352
1996	51.04369
1997	47.34099
1998	21.90831
1999	23.30305
2000	31.8721
2001	26.96492
2002	21.19022
2003	17.84975
2004	19.10037
2005	15.50721
2006	19.85402
2007	12.71173
2008	11.08106
2009	12.67294
2010	10.09834
2011	11.21642
2012	17.68349
2013	10.15188
2014	11.46987
2015	13.16896
2016	19.42691