Year	Percent
1960-01-01	62.390200000000000
1961-01-01	57.669300000000000
1962-01-01	53.708200000000000
1963-01-01	54.157700000000000
1964-01-01	53.510200000000000
1965-01-01	50.623900000000000
1966-01-01	48.915600000000000
1967-01-01	46.671700000000000
1968-01-01	42.943900000000000
1969-01-01	41.103700000000000
1970-01-01	39.070300000000000
1971-01-01	36.876800000000000
1972-01-01	37.323400000000000
1973-01-01	42.876600000000000
1974-01-01	50.844400000000000
1975-01-01	54.475700000000000
1976-01-01	54.554100000000000
1977-01-01	54.492300000000000
1978-01-01	50.472200000000000
1979-01-01	48.721800000000000
1980-01-01	50.194500000000000
1981-01-01	51.803700000000000
1982-01-01	48.135600000000000
1983-01-01	42.733900000000000
1984-01-01	38.327600000000000
1985-01-01	30.441300000000000
1986-01-01	26.909400000000000
1987-01-01	28.707200000000000
1988-01-01	36.642200000000000
1989-01-01	44.596400000000000
1990-01-01	45.297600000000000
1991-01-01	46.996400000000000
1992-01-01	49.530100000000000
1993-01-01	55.325900000000000
1994-01-01	56.502600000000000
1995-01-01	53.070300000000000
1996-01-01	52.048000000000000
1997-01-01	50.975900000000000
1998-01-01	51.086000000000006
1999-01-01	52.326000000000000
2000-01-01	54.176600000000000
2001-01-01	54.910900000000000
2002-01-01	54.226700000000000
2003-01-01	56.147900000000000
2004-01-01	58.834200000000000
2005-01-01	60.979200000000000
2006-01-01	63.933700000000000
2007-01-01	67.530900000000000
2008-01-01	72.975300000000000
2009-01-01	76.828300000000000
2010-01-01	79.169300000000000