Year	Percent
1974	69.46624
1976	68.94728
1977	71.83075
1978	70.96243
1979	71.21017
1980	74.53118
1985	88.95547
1986	91.21675
1987	94.55509
1988	94.42528
1989	94.5824
1990	97.13691
1991	97.35549
1992	94.97715
1993	96.92211
1994	97.5643
1995	95.95213
1996	96.62881
1997	97.36894
1998	94.75984
1999	97.62779
2000	99.71937
2001	96.94335
2002	97.43167
2003	93.50669
2004	92.83669
2005	97.4264
2006	100.77235
2007	105.59786
2008	108.04593
2009	106.38115
2010	104.05144
2013	102.26305
2014	103.64411
2015	102.55733