Year	Percent
1960	25.41365
1961	24.81465
1962	21.11705
1963	21.28666
1964	23.62402
1965	25.85786
1966	23.77021
1967	25.03951
1968	21.73933
1969	23.92637
1970	18.32431
1971	36.25064
1972	30.02
1973	35.11076
1974	48.20225
1975	49.95004
1976	51.72092
1977	63.6424
1978	62.30611
1979	58.29994
1980	66.3969
1981	63.39919
1982	54.95602
1983	63.77998
1984	74.45401
1985	74.20176
1986	44.34525
1987	46.80573
1988	49.81059
1989	58.54856
1990	62.49944
1991	77.57488
1992	68.80675
1993	110.30462
1994	88.61907
1995	72.03569
1996	64.56794
1997	68.97371
1998	59.57266
1999	62.56901
2000	64.0193
2001	67.13264
2002	43.17213
2003	51.56098
2004	60.09989
2005	63.44948
2006	58.61836
2007	60.94053
2008	65.47199
2009	53.48565
2010	34.74622
2011	41.77355
2012	35.9472
2013	30.7593
2014	27.12406
2015	20.66244
2016	18.28729
2017	24.4564