Year	Number of Years
1960-01-01	49.245
1961-01-01	49.773
1962-01-01	50.304
1963-01-01	50.828
1964-01-01	51.338
1965-01-01	51.838
1966-01-01	52.337
1967-01-01	52.845
1968-01-01	53.361
1969-01-01	53.879
1970-01-01	54.384
1971-01-01	54.858
1972-01-01	55.287
1973-01-01	55.659
1974-01-01	55.973
1975-01-01	56.224
1976-01-01	56.416
1977-01-01	56.564
1978-01-01	56.688
1979-01-01	56.802
1980-01-01	56.927
1981-01-01	57.077
1982-01-01	57.262
1983-01-01	57.490
1984-01-01	57.768
1985-01-01	58.101
1986-01-01	58.492
1987-01-01	58.927
1988-01-01	59.394
1989-01-01	59.880
1990-01-01	60.371
1991-01-01	60.854
1992-01-01	61.318
1993-01-01	61.755
1994-01-01	62.158
1995-01-01	62.526
1996-01-01	62.862
1997-01-01	63.174
1998-01-01	63.469
1999-01-01	63.745
2000-01-01	64.001
2001-01-01	64.231
2002-01-01	64.430
2003-01-01	64.599
2004-01-01	64.740
2005-01-01	64.859
2006-01-01	64.961
2007-01-01	65.054
2008-01-01	65.146
2009-01-01	65.244
2010-01-01	65.354
2011-01-01	65.481
2012-01-01	65.623
2013-01-01	65.780
2014-01-01	65.949
2015-01-01	66.130
2016-01-01	66.317