Year	Percent
1977	40.71378
1978	52.47094
1979	69.16095
1980	56.36247
1981	61.645
1982	56.92241
1983	51.62375
1984	62.23886
1985	62.95825
1986	70.88985
1987	67.31973
1988	66.60833
1989	66.30367
1990	75.15196
1991	76.78184
1992	81.57061
1993	82.08287
1994	74.04773
1995	69.56882
1996	63.5163
1997	65.13044
1998	64.00951
1999	61.71108
2000	56.23767
2001	55.6153
2002	52.5236
2003	54.06903
2004	58.06724
2005	53.34318
2006	47.37833
2007	44.32582
2008	45.69968
2009	45.87479
2010	45.45318
2011	47.08717
2012	44.85125
2013	45.73258
2014	46.14681
2015	44.12117
2016	41.70059