Year	Percent
1989	77.79942
1990	77.01256
1991	78.8199
1992	76.9813
1993	75.1004
1994	76.97427
1995	75.76264
1996	76.73948
1997	77.45822
1998	77.79001
1999	77.09619
2000	76.99301
2001	76.74897
2002	76.08622
2011	75.42247
2012	77.13561
2013	75.71512
2014	75.79751
2015	74.2253
2016	72.26615