Year	Percent
1960-01-01	62.5707
1961-01-01	64.4538
1962-01-01	65.1272
1963-01-01	64.2264
1964-01-01	64.2122
1965-01-01	66.0652
1966-01-01	68.2402
1967-01-01	66.5324
1968-01-01	70.3948
1969-01-01	80.7745
1970-01-01	84.3150
1971-01-01	88.2181
1972-01-01	94.5898
1973-01-01	94.2976
1974-01-01	84.7855
1975-01-01	78.1037
1976-01-01	76.8097
1977-01-01	74.8304
1978-01-01	77.4657
1979-01-01	81.1011
1980-01-01	83.0767
1981-01-01	83.1474
1982-01-01	83.1566
1983-01-01	85.2088
1984-01-01	83.6645
1985-01-01	87.4473
1986-01-01	92.5160
1987-01-01	91.5983
1988-01-01	93.4733
1989-01-01	94.3341
1990-01-01	94.8737
1991-01-01	95.6941
1992-01-01	96.5076
1993-01-01	97.0843
1994-01-01	96.7696
1995-01-01	96.5978
1996-01-01	96.5385
1997-01-01	96.5476
1998-01-01	96.7645
1999-01-01	97.4086
2000-01-01	97.8101
2001-01-01	97.7348
2002-01-01	97.6949
2003-01-01	97.7009
2004-01-01	97.5955
2005-01-01	97.5194
2006-01-01	97.7228
2007-01-01	98.0513
2008-01-01	98.2142
2009-01-01	98.1974
2010-01-01	98.2429