Year	Percent
1977	93.05102
1978	98.11409
1979	71.37204
1980	98.13875
1981	104.20046
1982	99.92804
1983	90.08341
1984	93.49108
1985	84.19115
1986	88.33443
1987	90.22689
1988	98.77116
1989	99.1041
1990	104.01496
1991	90.89043
1992	82.39498
1993	70.85174
1994	66.36986
1995	72.30947
1996	76.12782
1997	72.01519
1998	77.00024
1999	72.83165
2000	59.84889
2001	51.00266
2002	47.0838
2003	47.97378
2004	49.73858
2005	55.92375
2006	53.37726
2007	55.19229
2008	62.64058
2009	52.90443
2010	52.77159
2011	50.90546
2012	49.82819
2013	47.50973
2014	50.85013
2015	45.62099
2016	40.67867
2017	41.95252