Year	Percent
1971	96.27651
1972	95.60969
1973	92.44463
1974	92.41314
1975	93.85879
1976	97.28984
1977	105.18254
1978	104.68614
1979	104.72761
1980	103.01968
1981	96.7259
1982	91.79405
1983	94.1297
1984	97.86726
1987	100.5288
1988	98.17699
1989	96.11768
1990	95.97265
1991	96.44181
1992	100.82537
1993	107.15551
1994	105.2565
1999	100.46844
2000	100.21778
2001	102.01363
2002	102.46903
2003	106.57846
2004	103.08476
2005	99.8227
2006	95.56828
2007	95.35112
2008	93.9293
2009	93.67038
2010	96.42516
2011	100.6608
2012	102.96975
2013	102.25101
2014	100.89647
2015	104.03732