Year	Number of Years
1960-01-01	60.862
1961-01-01	61.379
1962-01-01	61.878
1963-01-01	62.359
1964-01-01	62.822
1965-01-01	63.272
1966-01-01	63.714
1967-01-01	64.156
1968-01-01	64.603
1969-01-01	65.059
1970-01-01	65.529
1971-01-01	66.015
1972-01-01	66.514
1973-01-01	67.019
1974-01-01	67.527
1975-01-01	68.028
1976-01-01	68.513
1977-01-01	68.977
1978-01-01	69.413
1979-01-01	69.819
1980-01-01	70.194
1981-01-01	70.539
1982-01-01	70.860
1983-01-01	71.165
1984-01-01	71.455
1985-01-01	71.734
1986-01-01	72.002
1987-01-01	72.261
1988-01-01	72.510
1989-01-01	72.752
1990-01-01	72.987
1991-01-01	73.218
1992-01-01	73.443
1993-01-01	73.663
1994-01-01	73.879
1995-01-01	74.090
1996-01-01	74.298
1997-01-01	74.501
1998-01-01	74.700
1999-01-01	74.895
2000-01-01	75.084
2001-01-01	75.267
2002-01-01	75.443
2003-01-01	75.614
2004-01-01	75.782
2005-01-01	75.947
2006-01-01	76.114
2007-01-01	76.285
2008-01-01	76.460
2009-01-01	76.641
2010-01-01	76.828
2011-01-01	77.021
2012-01-01	77.216
2013-01-01	77.413
2014-01-01	77.610
2015-01-01	77.806
2016-01-01	78.001