Year	Percent
1971	97.23508
1972	99.04146
1973	98.71887
1974	100.04572
1975	107.72231
1976	105.88597
1977	105.24575
1978	102.40812
1979	102.29254
1980	103.47602
1981	100.52002
1982	100.80841
1983	100.12865
1984	99.81733
1985	102.14259
1986	101.51962
1987	100.89242
1988	99.83568
1989	100.05068
1990	100.53458
1991	97.99751
1992	98.08826
1994	97.61437
1995	99.0195
1996	99.20268
1997	95.68092
1999	100.3288
2000	100.5441
2001	103.68998
2002	102.12734
2003	102.43138
2004	100.76527
2005	99.26483
2006	99.78058
2007	101.8026
2008	104.77043
2009	103.18969
2010	103.29948
2011	104.85611
2012	101.02462
2013	100.20795
2014	100.69997
2015	100.56113