Year	Percent
1972	48.71871
1973	57.3918
1974	46.44836
1975	56.17199
1976	60.44524
1977	63.33218
1978	65.04003
1979	71.51855
1980	73.61006
1981	74.32164
1982	73.10166
1983	70.04759
1984	71.34125
1985	70.19524
1986	72.33733
1987	73.8442
1988	73.25017
1989	67.2155
1990	58.35936
1991	49.73888
1992	61.9418
1993	62.05854
1994	52.37574
1996	49.2766
1999	31.76847
2001	56.25048
2002	58.48276
2003	54.15547
2004	76.77898
2005	67.49881
2006	72.10377
2007	71.43461
2008	66.54694
2009	65.07212
2010	65.24423
2011	72.95628
2012	74.46461