Year	%
1971	65.41002
1972	67.67922
1973	68.2199
1974	73.97375
1975	76.20108
1976	81.35779
1977	88.5776
1978	86.52142
1979	92.04022
1980	92.36386
1981	93.72145
1982	95.46411
1983	96.96789
1984	96.97441
1985	96.05666
1986	95.28214
1987	98.18404
1988	97.28368
1989	98.20953
1990	97.61598
1991	96.46729
1992	96.68051
1993	95.38422
1994	95.48533
1995	97.15158
1999	97.09979
2000	97.40409
2001	97.72621
2002	98.17643
2003	98.67255
2004	98.66557
2005	98.63525
2006	98.48928
2007	98.48444
2008	98.60332
2009	98.92307
2010	98.62642
2011	99.03107
2012	98.82599
2013	99.08836
2014	98.37158
2015	98.81487
2016	98.60992
2017	98.45096