Year	%
1970	49.92744
1971	54.5233
1979	59.03124
1980	56.67581
1981	53.39149
1982	52.87259
1983	54.05727
1984	53.47374
1985	58.16494
1986	59.11782
1987	62.29254
1988	63.17593
1989	64.73711
1990	64.19464
1991	66.76744
1992	67.09229
1993	67.89564
1994	68.73243
1995	68.68493
1999	84.75502
2000	82.92189
2001	87.88256
2004	96.80526
2005	98.15391
2006	96.71145
2007	96.93127
2008	94.56556
2009	92.02745
2010	92.9103
2011	94.02844
2012	84.37573
2013	84.83775
2014	83.64136
2015	84.64545
2016	85.28271
2017	91.70589