Year	Percent
1972	69.63024
1973	79.82422
1974	67.08998
1975	76.22312
1976	76.74548
1977	79.42128
1978	78.43528
1979	85.65279
1980	85.41363
1981	81.34529
1982	81.17851
1983	71.686
1984	76.60639
1985	72.49889
1986	72.43078
1987	71.88207
1988	73.40863
1989	68.09081
1990	59.25315
1991	58.92016
1992	61.22834
1993	63.93125
1994	54.80259
1996	48.67383
1999	30.6052
2001	56.23306
2002	59.71039
2003	57.44031
2004	83.85379
2005	72.51186
2006	79.48093
2007	76.44852
2008	70.60905
2009	70.03764
2010	69.509
2011	74.43974
2012	66.17179