Year	Percent
1971	0.41244
1973	0.42632
1974	0.44334
1975	0.47186
1976	0.47494
1977	0.46245
1978	0.47184
1979	0.46318
1980	0.4778
1981	0.50734
1983	0.53231
1984	0.55555
1985	0.56214
1986	0.5737
1987	0.5865
1989	0.58315
1992	0.65266
1993	0.66536
1994	0.68183
1995	0.69134
1996	0.73537
2008	1.01324
2009	1.01105
2010	0.99851