Year	Percent
1960-01-01	76.60240000000000
1961-01-01	76.38920000000000
1962-01-01	76.65430000000000
1963-01-01	77.41910000000000
1964-01-01	78.47580000000000
1965-01-01	79.93480000000000
1966-01-01	83.50700000000000
1967-01-01	86.82420000000000
1968-01-01	88.18480000000000
1969-01-01	88.81130000000000
1970-01-01	89.17940000000000
1971-01-01	89.42210000000000
1972-01-01	89.68570000000000
1973-01-01	90.16630000000000
1974-01-01	90.50800000000000
1975-01-01	90.67670000000000
1976-01-01	91.35670000000000
1977-01-01	91.83770000000000
1978-01-01	92.03810000000000
1979-01-01	92.43390000000000
1980-01-01	92.57910000000000
1981-01-01	93.46050000000000
1982-01-01	94.53280000000000
1983-01-01	94.67460000000000
1984-01-01	94.64350000000000
1985-01-01	95.21240000000000
1986-01-01	95.39930000000000
1987-01-01	95.15410000000000
1988-01-01	95.39160000000000
1989-01-01	95.84210000000000
1990-01-01	96.25570000000000
1991-01-01	96.41720000000000
1992-01-01	96.44200000000001
1993-01-01	96.53090000000000
1994-01-01	96.51870000000000
1995-01-01	96.68380000000000
1996-01-01	96.85380000000000
1997-01-01	96.85230000000000
1998-01-01	96.83860000000000
1999-01-01	96.61270000000000
2000-01-01	96.49040000000000
2001-01-01	97.14940000000000
2002-01-01	97.47900000000000
2003-01-01	97.43940000000000
2004-01-01	97.46230000000000
2005-01-01	97.54490000000000
2006-01-01	97.72130000000000
2007-01-01	97.77070000000000
2008-01-01	98.00290000000000