Year	Number of Years
1960-01-01	50.364
1961-01-01	50.944
1962-01-01	51.512
1963-01-01	52.063
1964-01-01	52.597
1965-01-01	53.118
1966-01-01	53.638
1967-01-01	54.165
1968-01-01	54.709
1969-01-01	55.272
1970-01-01	55.859
1971-01-01	56.476
1972-01-01	57.114
1973-01-01	57.758
1974-01-01	58.389
1975-01-01	58.977
1976-01-01	59.487
1977-01-01	59.902
1978-01-01	60.213
1979-01-01	60.425
1980-01-01	60.554
1981-01-01	60.628
1982-01-01	60.683
1983-01-01	60.750
1984-01-01	60.842
1985-01-01	60.969
1986-01-01	61.126
1987-01-01	61.297
1988-01-01	61.470
1989-01-01	61.641
1990-01-01	61.808
1991-01-01	61.972
1992-01-01	62.133
1993-01-01	62.294
1994-01-01	62.454
1995-01-01	62.611
1996-01-01	62.760
1997-01-01	62.902
1998-01-01	63.041
1999-01-01	63.181
2000-01-01	63.338
2001-01-01	63.526
2002-01-01	63.754
2003-01-01	64.021
2004-01-01	64.322
2005-01-01	64.641
2006-01-01	64.956
2007-01-01	65.248
2008-01-01	65.500
2009-01-01	65.709
2010-01-01	65.875
2011-01-01	66.008
2012-01-01	66.125
2013-01-01	66.241
2014-01-01	66.361
2015-01-01	66.488
2016-01-01	66.624