Year	Percent
1973-01-01	15.254300000000000
1974-01-01	15.004700000000000
1975-01-01	16.013500000000000
1976-01-01	19.427100000000000
1977-01-01	22.063700000000000
1978-01-01	23.397900000000000
1979-01-01	25.307200000000000
1980-01-01	24.266000000000000
1981-01-01	24.940200000000000
1982-01-01	25.813400000000000
1983-01-01	26.706900000000000
1984-01-01	28.621900000000000
1985-01-01	29.190100000000000
1986-01-01	30.280900000000000
1987-01-01	31.073800000000000
1988-01-01	30.665300000000000
1989-01-01	31.228700000000000
1990-01-01	31.254000000000000
1991-01-01	30.717500000000000
1992-01-01	31.563700000000000
1993-01-01	31.500700000000000
1994-01-01	31.951000000000000
1995-01-01	31.558000000000003
1996-01-01	31.021200000000000
1997-01-01	32.564800000000000
1998-01-01	33.559700000000000
1999-01-01	34.735400000000000
2000-01-01	39.719400000000000
2001-01-01	42.607700000000000
2002-01-01	47.051900000000000
2003-01-01	50.073000000000000
2004-01-01	52.122300000000000
2005-01-01	54.154700000000000
2006-01-01	55.220500000000000
2007-01-01	57.723000000000000
2008-01-01	62.416300000000000
2009-01-01	63.441300000000000
2010-01-01	62.244900000000000
2011-01-01	66.044600000000000
2012-01-01	67.337500000000000
2013-01-01	68.353800000000000
2014-01-01	68.684500000000000
2015-01-01	68.761900000000000
2016-01-01	69.673400000000000