Year	Percent
1964-01-01	5.992970000000000
1965-01-01	6.454410000000000
1966-01-01	6.892060000000001
1967-01-01	6.690080000000000
1968-01-01	6.471710000000000
1969-01-01	5.995200000000000
1970-01-01	8.140419999999999
1971-01-01	9.427400000000000
1972-01-01	9.937710000000001
1973-01-01	10.266500000000000
1974-01-01	10.581800000000000
1975-01-01	9.784540000000000
1976-01-01	10.807100000000000
1977-01-01	11.870100000000000
1978-01-01	12.233800000000000
1979-01-01	12.399500000000000
1980-01-01	12.417100000000000
1981-01-01	11.783100000000000
1982-01-01	11.624100000000000
1983-01-01	11.043500000000000
1984-01-01	11.101700000000000
1985-01-01	11.577200000000000
1986-01-01	13.414000000000001
1987-01-01	15.085500000000000
1988-01-01	16.044500000000000
1989-01-01	14.826300000000000
1990-01-01	14.550900000000000
1991-01-01	14.479700000000000
1992-01-01	13.510400000000000
1993-01-01	14.142200000000000
1994-01-01	14.142200000000000
1995-01-01	18.689900000000000
1996-01-01	15.830800000000000
1997-01-01	14.064600000000000
1998-01-01	14.877300000000000
1999-01-01	15.623100000000000
2000-01-01	15.673500000000000
2001-01-01	16.301300000000000
2002-01-01	16.815000000000000
2003-01-01	15.492900000000000
2004-01-01	16.039100000000000
2005-01-01	16.650100000000000
2006-01-01	15.861500000000000
2007-01-01	16.212000000000000
2008-01-01	16.030100000000000
2009-01-01	14.866700000000000
2010-01-01	14.840300000000000
2011-01-01	16.473900000000000
2012-01-01	17.625600000000000
2013-01-01	17.959200000000000
2014-01-01	18.603700000000000
2015-01-01	19.915300000000000
2016-01-01	19.987600000000000