Year	Percent
1960-01-01	18.359700000000000
1961-01-01	18.521700000000000
1962-01-01	16.865300000000000
1963-01-01	14.707000000000000
1964-01-01	15.927800000000000
1965-01-01	18.352999999999998
1966-01-01	17.414400000000000
1967-01-01	18.053900000000000
1968-01-01	17.571600000000000
1969-01-01	18.875999999999998
1970-01-01	18.776500000000000
1971-01-01	20.655200000000000
1972-01-01	23.491500000000000
1973-01-01	26.036800000000000
1974-01-01	28.741700000000000
1975-01-01	30.009200000000000
1976-01-01	30.211700000000000
1977-01-01	35.131500000000000
1978-01-01	37.868000000000000
1979-01-01	39.957500000000000
1980-01-01	40.039900000000000
1981-01-01	41.086000000000006
1982-01-01	41.334200000000000
1983-01-01	41.838700000000000
1984-01-01	37.118500000000000
1985-01-01	33.985800000000000
1986-01-01	33.737300000000000
1987-01-01	36.457300000000000
1988-01-01	38.198900000000000
1989-01-01	36.057500000000000
1990-01-01	36.455300000000000
1991-01-01	35.841900000000000
1992-01-01	34.253900000000000
1993-01-01	29.172100000000000
1994-01-01	20.444700000000000
1995-01-01	17.207300000000000
1996-01-01	16.347300000000000
1997-01-01	15.999200000000000
1998-01-01	16.076800000000000
1999-01-01	15.120700000000000
2000-01-01	14.749800000000000
2001-01-01	14.406300000000000
2002-01-01	13.869500000000000
2003-01-01	12.891800000000000
2004-01-01	12.855900000000000
2005-01-01	13.105300000000000
2006-01-01	13.317700000000000
2007-01-01	14.521400000000000
2008-01-01	15.151100000000000
2009-01-01	15.562999999999999
2010-01-01	15.793200000000000
2011-01-01	17.025700000000000
2012-01-01	15.809800000000000
2013-01-01	16.617500000000000
2014-01-01	17.926700000000000
2015-01-01	20.403200000000000
2016-01-01	22.032100000000000