Year	Percent
1973-01-01	41.358100000000000
1974-01-01	43.979400000000000
1975-01-01	48.612600000000000
1976-01-01	51.798000000000000
1977-01-01	50.428200000000000
1978-01-01	55.292800000000000
1979-01-01	51.695900000000000
1980-01-01	48.457400000000000
1981-01-01	52.371200000000000
1982-01-01	61.934600000000000
1983-01-01	65.437600000000000
1984-01-01	66.502300000000000
1985-01-01	69.171600000000000
1986-01-01	74.373400000000000
1987-01-01	73.973300000000000
1988-01-01	71.083000000000000
1989-01-01	64.207600000000000
1990-01-01	56.864400000000000
1991-01-01	44.481900000000000
1992-01-01	41.384800000000000
1993-01-01	40.781700000000000
1994-01-01	36.263400000000000
1995-01-01	31.255700000000000
1996-01-01	32.733000000000004
1997-01-01	34.307800000000000
1998-01-01	37.576400000000000
1999-01-01	38.555600000000000
2000-01-01	33.094300000000000
2001-01-01	37.795700000000000
2002-01-01	43.267100000000000
2003-01-01	41.176200000000000
2004-01-01	37.299600000000000
2005-01-01	33.329900000000000
2006-01-01	33.192700000000000
2007-01-01	32.572100000000000
2008-01-01	29.651100000000000
2009-01-01	36.745800000000000
2010-01-01	35.038000000000004
2011-01-01	33.119500000000000
2012-01-01	34.658600000000000
2013-01-01	37.589600000000000
2014-01-01	42.379600000000000
2015-01-01	51.449900000000000
2016-01-01	57.204200000000000