Year	Percent
1976-01-01	33.22360000000000
1977-01-01	28.57670000000000
1978-01-01	32.19820000000000
1979-01-01	28.27130000000000
1980-01-01	25.74460000000000
1981-01-01	25.74460000000000
1982-01-01	29.13170000000000
1983-01-01	30.79100000000000
1984-01-01	30.67580000000000
1985-01-01	31.43920000000000
1986-01-01	32.03080000000000
1987-01-01	33.07500000000000
1988-01-01	32.54790000000000
1989-01-01	31.60230000000000
1990-01-01	32.41650000000000
1991-01-01	33.80930000000000
1992-01-01	32.64050000000000
1993-01-01	32.62720000000000
1994-01-01	33.40170000000000
1995-01-01	35.51750000000000
1996-01-01	39.11340000000000
1997-01-01	42.33870000000000
1998-01-01	44.12870000000000
1999-01-01	44.88650000000000
2000-01-01	44.86920000000000
2001-01-01	48.39720000000000
2002-01-01	48.65850000000000
2003-01-01	47.52620000000000
2004-01-01	49.03890000000000
2005-01-01	51.54200000000000
2006-01-01	52.69150000000000
2007-01-01	57.21760000000000
2008-01-01	63.58620000000000
2009-01-01	70.11120000000000
2010-01-01	71.18940000000000
2011-01-01	68.74320000000000
2012-01-01	68.23899999999999
2013-01-01	69.72690000000000
2014-01-01	68.96020000000000
2015-01-01	71.75920000000000
2016-01-01	75.04930000000000