Year	Percent
1970	76.48776
1971	76.72574
1972	86.36866
1973	90.31843
1974	88.93227
1975	86.63399
1976	81.92198
1977	89.02445
1978	85.62152
1979	82.86777
1980	83.46024
1981	87.11617
1982	87.77172
1983	81.60789
1984	74.92113
1985	78.14954
1986	78.68407
1987	75.86149
1988	76.2366
1989	75.64157
1990	75.05985
1991	79.76425
1992	81.80667
1993	83.72751
1994	82.46382
1995	81.76579
1996	83.92414
1999	86.56073
2000	92.11182
2001	94.77646
2002	96.69088
2004	96.4625
2005	95.44037
2006	91.70082
2007	93.73183
2008	95.05981
2009	98.13118
2010	99.36927
2011	104.53825
2012	102.6313
2013	98.9648
2014	98.73826
2015	99.46631
2016	96.44022