Year	Percent
1974	39.088
1975	41.20807
1976	48.78446
1977	55.89371
1978	59.73071
1979	64.61905
1980	66.9854
1981	71.11978
1982	80.47976
1983	79.88308
1984	76.88124
1985	73.02932
1986	74.63995
1987	75.0894
1988	73.4687
1989	80.83627
1990	89.60274
1991	96.03876
1992	94.51808
1993	92.03414
1994	90.80233
1995	88.81563
1996	84.85301
1997	86.83647
1998	84.43131
1999	83.09341
2000	79.81954
2001	76.23124
2002	80.13654
2007	97.16235
2009	84.88686
2010	84.48627
2011	87.35031
2012	95.00613
2013	96.98742
2014	100.74221
2015	105.18609