Year	Number of Years
1960-01-01	59.253
1961-01-01	59.829
1962-01-01	60.395
1963-01-01	60.948
1964-01-01	61.488
1965-01-01	62.017
1966-01-01	62.539
1967-01-01	63.056
1968-01-01	63.570
1969-01-01	64.076
1970-01-01	64.569
1971-01-01	65.041
1972-01-01	65.485
1973-01-01	65.899
1974-01-01	66.279
1975-01-01	66.630
1976-01-01	66.956
1977-01-01	67.265
1978-01-01	67.560
1979-01-01	67.844
1980-01-01	68.114
1981-01-01	68.365
1982-01-01	68.593
1983-01-01	68.795
1984-01-01	68.975
1985-01-01	69.133
1986-01-01	69.274
1987-01-01	69.403
1988-01-01	69.529
1989-01-01	69.659
1990-01-01	69.804
1991-01-01	69.971
1992-01-01	70.165
1993-01-01	70.384
1994-01-01	70.628
1995-01-01	70.893
1996-01-01	71.176
1997-01-01	71.465
1998-01-01	71.752
1999-01-01	72.027
2000-01-01	72.281
2001-01-01	72.507
2002-01-01	72.704
2003-01-01	72.872
2004-01-01	73.015
2005-01-01	73.134
2006-01-01	73.235
2007-01-01	73.327
2008-01-01	73.419
2009-01-01	73.516
2010-01-01	73.625
2011-01-01	73.748
2012-01-01	73.885
2013-01-01	74.035
2014-01-01	74.196
2015-01-01	74.367
2016-01-01	74.545