Year	Percent
1980-01-01	18.213000000000000
1981-01-01	16.037900000000000
1982-01-01	19.088200000000000
1983-01-01	20.521000000000000
1984-01-01	19.576700000000000
1985-01-01	19.873900000000000
1986-01-01	18.736100000000000
1987-01-01	16.769300000000000
1988-01-01	14.739200000000000
1989-01-01	17.273100000000000
1990-01-01	16.478600000000000
1991-01-01	20.369000000000000
1992-01-01	22.812400000000000
1993-01-01	25.155700000000000
1994-01-01	25.584400000000000
1995-01-01	22.540200000000000
1996-01-01	22.788700000000000
1997-01-01	20.112900000000000
1998-01-01	18.711200000000000
1999-01-01	21.191000000000000
2000-01-01	17.227999999999998
2001-01-01	15.948400000000000
2002-01-01	14.999100000000000
2003-01-01	15.817400000000000
2004-01-01	14.866200000000000
2005-01-01	14.792600000000000
2006-01-01	14.063100000000000
2007-01-01	24.096400000000000
2008-01-01	24.518600000000000
2009-01-01	28.349700000000000
2010-01-01	31.015900000000000
2011-01-01	30.657600000000000
2012-01-01	38.393700000000000
2013-01-01	41.563500000000000
2014-01-01	42.361500000000000
2015-01-01	40.835600000000000
2016-01-01	38.609800000000000