Year	Percent
1960-01-01	12.468800000000000
1961-01-01	12.304200000000000
1962-01-01	11.969200000000000
1963-01-01	12.619900000000000
1964-01-01	13.368000000000000
1965-01-01	13.205200000000000
1966-01-01	12.699000000000002
1967-01-01	14.228900000000000
1968-01-01	15.023900000000000
1969-01-01	14.005900000000000
1970-01-01	13.276800000000000
1971-01-01	15.794600000000000
1972-01-01	18.258200000000000
1973-01-01	18.401000000000000
1974-01-01	18.983400000000000
1975-01-01	19.974600000000000
1976-01-01	21.968600000000000
1977-01-01	23.127900000000000
1978-01-01	25.671900000000000
1979-01-01	28.232800000000000
1980-01-01	29.546300000000000
1981-01-01	29.570400000000000
1982-01-01	30.197400000000000
1983-01-01	30.882100000000000
1984-01-01	31.158100000000000
1985-01-01	30.822900000000000
1986-01-01	29.076800000000000
1987-01-01	30.108800000000000
1988-01-01	30.919000000000000
1989-01-01	31.875300000000000
1990-01-01	31.860400000000000
1991-01-01	25.535800000000000
1992-01-01	25.517900000000000
1993-01-01	24.992900000000000
1994-01-01	24.360500000000000
1995-01-01	22.042500000000000
1996-01-01	23.924800000000000
1997-01-01	18.223800000000000
1998-01-01	10.258300000000000
1999-01-01	10.920100000000000
2000-01-01	12.945100000000000
2001-01-01	15.223100000000000
2002-01-01	16.801000000000000
2003-01-01	17.983200000000000
2004-01-01	19.026700000000000
2005-01-01	20.207900000000000
2006-01-01	21.133800000000000
2007-01-01	21.750500000000000
2008-01-01	21.760600000000000
2009-01-01	22.966300000000000
2010-01-01	23.855999999999998
2011-01-01	23.878200000000000
2012-01-01	23.277100000000000
2013-01-01	24.099400000000000
2014-01-01	24.648000000000003
2015-01-01	25.518800000000000
2016-01-01	26.429700000000000