Year	Number of Years
1960-01-01	62.279
1961-01-01	63.298
1962-01-01	64.187
1963-01-01	64.911
1964-01-01	65.461
1965-01-01	65.848
1966-01-01	66.108
1967-01-01	66.302
1968-01-01	66.485
1969-01-01	66.687
1970-01-01	66.933
1971-01-01	67.235
1972-01-01	67.580
1973-01-01	67.951
1974-01-01	68.341
1975-01-01	68.734
1976-01-01	69.108
1977-01-01	69.447
1978-01-01	69.741
1979-01-01	69.990
1980-01-01	70.207
1981-01-01	70.416
1982-01-01	70.635
1983-01-01	70.876
1984-01-01	71.134
1985-01-01	71.388
1986-01-01	71.605
1987-01-01	71.760
1988-01-01	71.843
1989-01-01	71.860
1990-01-01	71.836
1991-01-01	71.803
1992-01-01	71.802
1993-01-01	71.860
1994-01-01	71.992
1995-01-01	72.205
1996-01-01	72.495
1997-01-01	72.838
1998-01-01	73.208
1999-01-01	73.588
2000-01-01	73.955
2001-01-01	74.286
2002-01-01	74.575
2003-01-01	74.820
2004-01-01	75.028
2005-01-01	75.217
2006-01-01	75.418
2007-01-01	75.656
2008-01-01	75.943
2009-01-01	76.281
2010-01-01	76.652
2011-01-01	77.031
2012-01-01	77.389
2013-01-01	77.702
2014-01-01	77.963
2015-01-01	78.174
2016-01-01	78.345