Year	Percent
1971	93.14578
1972	93.05189
1973	89.37982
1974	90.22876
1975	91.76917
1976	96.27103
1977	102.93073
1978	104.03451
1979	104.94986
1980	103.35591
1981	96.23205
1982	92.18597
1983	92.77505
1984	98.19547
1987	100.67685
1988	98.34559
1989	96.29294
1990	96.95806
1991	96.14143
1992	100.21005
1993	105.08329
1994	103.35239
1999	100.34525
2000	98.92328
2001	102.49675
2002	102.70941
2003	106.40413
2004	105.0404
2005	100.42917
2006	95.63248
2007	94.84841
2008	94.62919
2009	92.78788
2010	96.98616
2011	102.09723
2012	102.40961
2013	102.66902
2014	101.14893
2015	103.51805