Year	Percent
1977	52.63824
1978	59.35707
1979	57.35675
1980	55.64846
1981	52.86442
1982	52.22906
1983	52.698
1984	52.17342
1985	50.84447
1986	50.26093
1987	50.10949
1988	49.07335
1989	50.69729
1990	51.59428
1991	53.89841
1992	55.7688
1993	60.53309
1994	61.62164
1996	72.92946
1999	96.87593
2000	98.04985
2001	98.70727
2002	99.27622
2003	99.7749
2004	100.61358
2005	97.98086
2006	94.93777
2007	94.17675
2008	95.10766
2009	97.51052
2010	97.5389
2011	97.60779
2012	98.50026
2013	97.13784
2014	96.13387
2015	96.78473
2016	97.45344