Year	Percent
1975-01-01	15.153900000000000
1976-01-01	17.601100000000000
1977-01-01	21.059500000000000
1978-01-01	23.093200000000000
1979-01-01	18.735800000000000
1980-01-01	16.984100000000000
1981-01-01	16.417300000000000
1982-01-01	16.294000000000000
1983-01-01	17.869100000000000
1984-01-01	18.144300000000000
1985-01-01	19.708300000000000
1986-01-01	19.855100000000000
1987-01-01	20.615000000000000
1988-01-01	20.295600000000000
1989-01-01	19.104300000000000
1990-01-01	19.803000000000000
1991-01-01	19.857700000000000
1992-01-01	19.732100000000000
1993-01-01	19.586500000000000
1994-01-01	21.912000000000000
1995-01-01	23.166800000000000
1996-01-01	23.214000000000002
1997-01-01	25.809400000000000
1998-01-01	27.098500000000000
1999-01-01	27.944500000000000
2000-01-01	30.255800000000000
2001-01-01	32.156900000000000
2002-01-01	31.840000000000000
2003-01-01	32.590800000000000
2004-01-01	34.521800000000000
2005-01-01	36.198400000000000
2006-01-01	37.854900000000000
2007-01-01	39.169700000000000
2008-01-01	41.349100000000000
2009-01-01	38.966400000000000
2010-01-01	37.240800000000000
2011-01-01	36.417900000000000
2012-01-01	37.433800000000000
2013-01-01	39.745600000000000
2014-01-01	40.844700000000000
2015-01-01	43.205200000000000
2016-01-01	46.808600000000000