Year	%
1972	61.10623
1973	59.22768
1974	60.35848
1976	60.5805
1977	60.77083
1978	61.3158
1979	61.47118
1980	61.64817
1981	57.00211
1982	57.4752
1983	58.2458
1984	57.38166
1985	60.616
1986	61.36594
1987	63.18577
1988	63.36002
1989	64.07405
1990	63.95933
1991	63.27177
1992	63.48114
1993	62.37844
1994	63.84253
1995	65.0141
1996	66.86841
1997	67.06207
1998	70.25506
1999	69.34246
2000	70.82322
2001	72.49969
2002	73.73853
2003	75.4207
2004	78.29793
2005	78.72206
2006	80.65417
2007	81.73872
2008	78.81053
2009	79.52286
2010	79.92946
2011	80.77601
2012	78.1264
2013	78.55168
2014	77.61063
2015	79.01426
2016	77.63698