Year	Percent
1975-01-01	51.7585
1976-01-01	45.9507
1977-01-01	43.7814
1978-01-01	41.8964
1979-01-01	40.0028
1980-01-01	39.5639
1981-01-01	39.6457
1982-01-01	47.4908
1983-01-01	49.6781
1984-01-01	44.2624
1985-01-01	45.0207
1986-01-01	46.2486
1987-01-01	51.4819
1988-01-01	52.7498
1989-01-01	56.5416
1990-01-01	54.7513
1991-01-01	56.4609
1992-01-01	54.2805
1993-01-01	55.4567
1994-01-01	55.7949
1995-01-01	57.0127
1996-01-01	59.6438
1997-01-01	61.1842
1998-01-01	60.9095
1999-01-01	62.8508
2000-01-01	66.3649
2001-01-01	73.7526
2002-01-01	73.1134
2003-01-01	70.9863
2004-01-01	71.6743
2005-01-01	73.8774
2006-01-01	74.8948
2007-01-01	74.0657
2008-01-01	79.5583
2009-01-01	84.8783
2010-01-01	81.5898
2011-01-01	79.0581
2012-01-01	81.1114
2013-01-01	80.1909
2014-01-01	80.8387
2015-01-01	78.1074
2016-01-01	79.0894