Year	Percent
1968	39.48595
1969	36.576
1970	37.45456
1971	38.25564
1972	37.89662
1973	41.66346
1974	52.45968
1975	44.90563
1976	44.49372
1977	43.38641
1978	41.98954
1979	45.04372
1980	45.12764
1981	43.28763
1982	40.3787
1983	36.40497
1984	50.03992
1985	48.33785
1986	48.66742
1987	47.86111
1988	50.16773
1989	55.22944
1990	59.67566
1991	55.2784
1992	53.2093
1993	50.28595
1994	42.23199
1995	38.90836
1996	46.25324
1997	46.35359
1998	40.57408
1999	41.94066
2000	46.40485
2001	42.91029
2002	46.65497
2003	48.84171
2004	51.11348
2005	53.0884
2006	51.92766
2007	49.28286
2008	50.61246
2009	40.81209
2010	48.4086
2011	48.63213
2012	45.1602
2013	44.72616
2014	37.24469