Year	Percent
1971	74.69703
1972	79.1284
1973	78.29596
1974	82.12345
1975	87.70294
1976	91.89166
1977	95.00536
1978	96.5974
1979	92.29132
1980	89.04114
1981	89.01714
1982	93.13147
1983	94.03554
1984	93.19805
1985	94.38665
1986	94.66205
1987	94.43298
1988	93.71629
1989	94.37728
1990	94.99793
1991	96.34646
1992	100.70155
1993	92.71444
1994	94.72373
1995	93.23066
1996	94.55466
1997	95.0854
1998	94.64504
1999	95.2151
2000	94.43108
2001	95.85133
2002	98.46089
2003	106.96697
2004	108.55294
2005	109.45024
2006	108.67145
2007	106.02107
2008	104.17419
2009	103.47757
2010	104.62643
2011	108.00171
2012	110.13153
2013	66.16785