Year	Percent
1970	13.19158
1971	16.99342
1972	19.14617
1973	13.79167
1974	14.07315
1975	23.38979
1976	25.54743
1977	27.13789
1978	26.66937
1979	24.45016
1980	28.00327
1981	38.03962
1982	52.22976
1983	61.70837
1984	59.1965
1985	69.95089
1986	84.54087
1987	75.62257
1988	55.71269
1989	44.39627
1990	36.36796
1991	36.59862
1992	35.73152
1993	41.05997
1994	42.79167
1995	40.6097
1996	41.25556
1997	49.89885
1998	62.1252
1999	56.99272
2000	48.67151
2001	52.48419
2002	51.29285
2003	48.69323
2004	51.13798
2005	47.30737
2006	44.3425
2007	44.44562
2008	47.74087
2009	60.34139
2010	54.19082
2011	49.81158
2012	64.02075
2013	60.40263
2014	60.17358
2015	66.30823
2016	69.57507