Year	Number of Years
1960-01-01	57.867
1961-01-01	58.173
1962-01-01	58.476
1963-01-01	58.775
1964-01-01	59.072
1965-01-01	59.368
1966-01-01	59.668
1967-01-01	59.970
1968-01-01	60.270
1969-01-01	60.563
1970-01-01	60.832
1971-01-01	61.063
1972-01-01	61.245
1973-01-01	61.381
1974-01-01	61.475
1975-01-01	61.544
1976-01-01	61.605
1977-01-01	61.681
1978-01-01	61.792
1979-01-01	61.946
1980-01-01	62.155
1981-01-01	62.421
1982-01-01	62.732
1983-01-01	63.073
1984-01-01	63.434
1985-01-01	63.798
1986-01-01	64.149
1987-01-01	64.475
1988-01-01	64.770
1989-01-01	65.029
1990-01-01	65.256
1991-01-01	65.461
1992-01-01	65.657
1993-01-01	65.856
1994-01-01	66.059
1995-01-01	66.265
1996-01-01	66.471
1997-01-01	66.668
1998-01-01	66.851
1999-01-01	67.019
2000-01-01	67.170
2001-01-01	67.308
2002-01-01	67.434
2003-01-01	67.555
2004-01-01	67.670
2005-01-01	67.783
2006-01-01	67.892
2007-01-01	68.000
2008-01-01	68.105
2009-01-01	68.211
2010-01-01	68.320
2011-01-01	68.433
2012-01-01	68.553
2013-01-01	68.680
2014-01-01	68.813
2015-01-01	68.951
2016-01-01	69.094