Year	Percent
1974-01-01	9.670960000000001
1975-01-01	8.254910000000000
1976-01-01	8.581380000000001
1977-01-01	9.224860000000001
1978-01-01	9.360130000000000
1979-01-01	10.145200000000000
1980-01-01	9.323490000000000
1981-01-01	10.160700000000000
1982-01-01	11.060300000000000
1983-01-01	12.027500000000000
1984-01-01	13.626700000000000
1985-01-01	15.080900000000000
1986-01-01	15.080900000000000
1987-01-01	15.080900000000000
1988-01-01	15.080900000000000
1989-01-01	15.080900000000000
1990-01-01	15.080900000000000
1991-01-01	15.080900000000000
1992-01-01	15.080900000000000
1993-01-01	19.057200000000000
1994-01-01	18.220500000000000
1995-01-01	19.958900000000000
1996-01-01	21.614100000000000
1997-01-01	22.907500000000000
1998-01-01	23.577200000000000
1999-01-01	23.841100000000000
2000-01-01	24.991200000000000
2001-01-01	30.465300000000000
2002-01-01	36.172600000000000
2003-01-01	37.130800000000000
2004-01-01	38.299700000000000
2005-01-01	39.932500000000000
2006-01-01	40.758000000000000
2007-01-01	41.555400000000000
2008-01-01	43.580900000000000
2009-01-01	45.392300000000000
2010-01-01	47.592800000000000
2011-01-01	50.748700000000000
2012-01-01	51.289700000000000
2013-01-01	52.375900000000000
2014-01-01	54.646700000000000
2015-01-01	55.705600000000000
2016-01-01	55.865400000000000