Year	Percent
1967-01-01	12.3909000000000000
1968-01-01	11.8415000000000000
1969-01-01	13.2956000000000000
1970-01-01	13.9029000000000000
1971-01-01	15.2414000000000000
1972-01-01	16.1291000000000000
1973-01-01	14.3612000000000000
1974-01-01	14.9306000000000000
1975-01-01	14.4082000000000000
1976-01-01	13.8168000000000000
1977-01-01	15.2513000000000000
1978-01-01	16.3733000000000000
1979-01-01	18.8104000000000000
1980-01-01	21.1226000000000000
1981-01-01	21.4769999999999970
1982-01-01	24.1577000000000000
1983-01-01	26.4429000000000000
1984-01-01	27.1463000000000000
1985-01-01	28.5939000000000000
1986-01-01	29.3490000000000000
1987-01-01	31.1134000000000000
1988-01-01	26.5677000000000000
1989-01-01	28.6244000000000000
1990-01-01	26.2395000000000000
1991-01-01	27.5187000000000000
1992-01-01	26.6298000000000000
1993-01-01	17.4153000000000000
1994-01-01	5.3981800000000000
1995-01-01	3.6312599999999997
1996-01-01	7.1286200000000000
1997-01-01	10.7533000000000000
1998-01-01	11.6515000000000000
1999-01-01	11.1453000000000000
2000-01-01	6.2781699999999990
2001-01-01	5.0938000000000000
2002-01-01	8.1238200000000000
2003-01-01	11.6743000000000000
2004-01-01	12.9735000000000000
2005-01-01	13.6114000000000000
2006-01-01	14.7450000000000000
2007-01-01	17.2081000000000000
2008-01-01	20.2539000000000000
2009-01-01	22.1939000000000000
2010-01-01	22.8363000000000000
2011-01-01	22.7050000000000000
2012-01-01	22.5014000000000000
2013-01-01	25.5271000000000000
2014-01-01	28.7456000000000000
2015-01-01	31.2898000000000000
2016-01-01	31.5429000000000000