Year	%
1978	80.51132
1979	80.46995
1980	80.04122
1981	78.6472
1982	77.07471
1983	76.76563
1984	79.94024
1985	79.38822
1986	78.97022
1987	78.5573
1988	78.0137
1989	77.66212
1990	77.91935
1991	78.28561
1992	78.48905
1993	77.7702
1994	78.71883
1995	79.17852
1996	82.68068
1997	80.26085
1998	80.90044
1999	82.60675
2000	81.21226
2001	83.25572
2002	84.18459
2009	92.18755
2010	92.14009
2011	91.96948
2012	92.58249
2013	93.07124
2014	93.63557
2015	94.12959
2016	94.09417