Year	Percent
1971	95.7632
1972	93.21425
1973	91.57472
1974	91.86518
1976	88.15439
1977	93.24825
1978	87.46103
1979	87.39526
1980	79.51144
1981	82.86505
1982	84.63398
1983	80.69239
1984	85.42352
1987	87.93468
1992	91.28767
1993	89.85417
1995	76.68533
1996	80.18394
1997	84.57112
1999	100.40083
2000	102.85714
2001	87.60798
2003	74.55974
2005	91.45706
2006	92.50493
2007	93.30269
2008	95.53241
2009	99.49375
2010	94.44038
2011	99.16758
2012	97.67211