Year	Percent
1970	7.88618
1971	3.68548
1972	2.80945
1973	9.23907
1974	9.69195
1975	10.37694
1976	11.39895
1977	9.61236
1978	9.34838
1979	10.26294
1980	13.05127
1981	18.74324
1982	19.10873
1983	21.33794
1984	18.88657
1985	18.90982
1986	20.57844
1987	24.22698
1988	25.48588
1989	25.36399
1990	27.3451
1991	28.28106
1992	28.27238
1993	36.57481
1994	40.99257
1995	38.84015
1996	37.98341
1997	35.12648
1998	37.87138
1999	52.20063
2000	51.73166
2001	47.16254
2002	39.52975
2003	43.51193
2004	46.4333
2005	48.47614
2006	41.60451
2007	32.06404
2008	34.52018
2009	37.17145
2010	44.23669
2011	45.8486
2012	41.80234
2013	43.21976
2014	46.85759
2015	46.46759
2016	48.32819