Year	Percent
1960-01-01	30.15040000000000
1961-01-01	29.01560000000000
1962-01-01	26.64320000000000
1963-01-01	24.67150000000000
1964-01-01	23.66150000000000
1965-01-01	22.46580000000000
1966-01-01	22.01610000000000
1967-01-01	21.75360000000000
1968-01-01	20.41510000000000
1969-01-01	19.68640000000000
1970-01-01	19.43380000000000
1971-01-01	18.88500000000000
1972-01-01	20.42870000000000
1973-01-01	23.98820000000000
1974-01-01	26.15780000000000
1975-01-01	24.62340000000000
1976-01-01	23.43380000000000
1977-01-01	25.96280000000000
1978-01-01	27.08510000000000
1979-01-01	28.47790000000000
1980-01-01	26.94360000000000
1981-01-01	26.05120000000000
1982-01-01	26.45620000000000
1983-01-01	26.12020000000000
1984-01-01	25.80160000000000
1985-01-01	28.45340000000000
1986-01-01	31.26710000000000
1987-01-01	34.15830000000000
1988-01-01	49.88370000000000
1989-01-01	66.15899999999999
1990-01-01	68.58400000000000
1991-01-01	70.43170000000000
1992-01-01	72.69080000000000
1993-01-01	74.28630000000000
1994-01-01	73.97750000000000
1995-01-01	75.73510000000000
1996-01-01	79.65980000000000
1997-01-01	83.14570000000000
1998-01-01	83.16850000000000
1999-01-01	84.26740000000000
2000-01-01	83.48040000000000
2001-01-01	82.78130000000000
2002-01-01	80.64200000000000
2003-01-01	80.08350000000000
2004-01-01	80.04990000000000
2005-01-01	79.80880000000000
2006-01-01	83.79130000000000
2007-01-01	87.88380000000000
2008-01-01	90.24330000000000
2009-01-01	92.50990000000000
2010-01-01	93.40170000000000