Year	Percent
1973-01-01	26.799700000000000
1974-01-01	27.733000000000000
1975-01-01	28.470500000000000
1976-01-01	28.200200000000000
1977-01-01	27.311400000000000
1978-01-01	29.316500000000000
1979-01-01	33.352900000000000
1980-01-01	37.209300000000000
1981-01-01	29.216300000000000
1982-01-01	20.326100000000000
1983-01-01	21.203000000000003
1984-01-01	21.501600000000000
1985-01-01	20.813800000000000
1986-01-01	19.084500000000000
1987-01-01	19.550500000000000
1988-01-01	19.211400000000000
1989-01-01	18.560900000000000
1990-01-01	18.374400000000000
1991-01-01	12.994500000000000
1992-01-01	11.980300000000000
1993-01-01	13.218100000000000
1994-01-01	14.252200000000000
1995-01-01	12.851300000000000
1996-01-01	13.879700000000000
1997-01-01	17.104900000000000
1998-01-01	19.781700000000000
1999-01-01	22.928700000000000
2000-01-01	26.371100000000000
2001-01-01	29.519800000000000
2002-01-01	32.496300000000000
2003-01-01	35.014400000000000
2004-01-01	37.587900000000000
2005-01-01	39.688200000000000
2006-01-01	39.504000000000000
2007-01-01	41.474400000000000
2008-01-01	46.461700000000000
2009-01-01	50.006000000000000
2010-01-01	48.513900000000000
2011-01-01	48.881500000000000
2012-01-01	50.506600000000000
2013-01-01	54.074000000000000
2014-01-01	56.630500000000000
2015-01-01	60.063800000000000
2016-01-01	63.692000000000000