Year	Percent
1960-01-01	20.510300000000000
1961-01-01	19.614800000000000
1962-01-01	18.179800000000000
1963-01-01	18.344100000000000
1964-01-01	19.427500000000000
1965-01-01	20.430800000000000
1966-01-01	21.914700000000000
1967-01-01	23.857400000000000
1968-01-01	24.820100000000000
1969-01-01	27.175400000000000
1970-01-01	27.395000000000000
1971-01-01	29.357500000000000
1972-01-01	33.768300000000000
1973-01-01	35.615500000000000
1974-01-01	30.415200000000000
1975-01-01	40.404100000000000
1976-01-01	47.163800000000000
1977-01-01	51.514200000000000
1978-01-01	57.455600000000000
1979-01-01	53.310500000000000
1980-01-01	50.282500000000000
1981-01-01	52.899100000000000
1982-01-01	58.970300000000000
1983-01-01	68.955400000000000
1984-01-01	58.216100000000000
1985-01-01	58.163100000000000
1986-01-01	56.901900000000000
1987-01-01	45.591500000000000
1988-01-01	40.537600000000000
1989-01-01	31.759800000000000
1990-01-01	31.754500000000000
1991-01-01	35.942000000000000
1992-01-01	34.806999999999995
1993-01-01	32.290000000000000
1994-01-01	28.351500000000000
1995-01-01	25.450200000000000
1996-01-01	17.165300000000000
1997-01-01	18.762900000000000
1998-01-01	20.032400000000000
1999-01-01	19.543700000000000
2000-01-01	18.656400000000000
2001-01-01	19.021500000000000
2002-01-01	17.055800000000000
2003-01-01	19.525800000000000
2004-01-01	18.395500000000000
2005-01-01	19.002500000000000
2006-01-01	24.384300000000000
2007-01-01	31.733400000000000
2008-01-01	26.387400000000000
2009-01-01	31.995300000000000
2010-01-01	28.936000000000000
2011-01-01	30.093700000000000
2012-01-01	36.317600000000000
2013-01-01	42.629000000000000