Year	Percent
1974	66.80726
1976	69.74058
1977	68.71117
1978	67.56261
1979	69.8086
1980	70.83707
1985	85.14393
1986	84.92872
1987	89.09329
1988	89.86486
1989	91.19021
1990	91.91314
1991	92.466
1992	90.58767
1993	92.14142
1994	92.1079
1995	92.82275
1996	92.26769
1997	94.29279
1998	96.91463
1999	94.91159
2000	94.99964
2001	93.86377
2002	92.4158
2003	90.08841
2004	91.56446
2005	93.35947
2006	98.36149
2007	102.73872
2008	104.89112
2009	105.37906
2010	104.61936
2013	103.68755
2014	102.92478
2015	101.82436