Year	Percent
1960-01-01	18.7678
1961-01-01	18.3975
1962-01-01	24.8860
1963-01-01	27.7082
1964-01-01	26.1409
1965-01-01	28.0602
1966-01-01	29.1944
1967-01-01	30.4138
1968-01-01	32.2716
1969-01-01	34.1897
1970-01-01	36.8944
1971-01-01	42.1584
1972-01-01	45.5975
1973-01-01	45.2968
1974-01-01	56.5654
1975-01-01	74.9773
1976-01-01	73.4041
1977-01-01	73.0771
1978-01-01	75.8062
1979-01-01	75.1250
1980-01-01	70.8217
1981-01-01	65.5681
1982-01-01	63.6456
1983-01-01	63.7258
1984-01-01	62.7470
1985-01-01	62.2656
1986-01-01	61.3496
1987-01-01	60.6539
1988-01-01	59.0185
1989-01-01	58.8545
1990-01-01	58.0542
1991-01-01	58.3830
1992-01-01	59.4898
1993-01-01	61.4709
1994-01-01	60.7069
1995-01-01	57.6541
1996-01-01	55.5875
1997-01-01	52.1183
1998-01-01	48.8065
1999-01-01	53.0780
2000-01-01	55.2314
2001-01-01	54.9954
2002-01-01	56.3077
2003-01-01	59.8942
2004-01-01	61.5524
2005-01-01	62.8113
2006-01-01	63.8963
2007-01-01	68.8289
2008-01-01	76.5904
2009-01-01	82.7654
2010-01-01	82.3051
2011-01-01	79.9434
2012-01-01	82.6118
2013-01-01	85.4350
2014-01-01	86.9605
2015-01-01	88.7415
2016-01-01	90.9222