Year	Percent
1975	44.08809
1980	67.40672
1981	61.99127
1982	55.35252
1983	52.85326
1984	48.84806
1986	52.65664
1990	60.08055
1991	71.64878
1992	68.8482
1993	70.12755
1994	72.48122
2010	84.86022
2011	85.55439
2012	85.10576