Year	Number of Years
1960-01-01	64.828
1961-01-01	65.301
1962-01-01	65.757
1963-01-01	66.199
1964-01-01	66.629
1965-01-01	67.055
1966-01-01	67.486
1967-01-01	67.928
1968-01-01	68.388
1969-01-01	68.865
1970-01-01	69.360
1971-01-01	69.869
1972-01-01	70.384
1973-01-01	70.897
1974-01-01	71.400
1975-01-01	71.887
1976-01-01	72.352
1977-01-01	72.793
1978-01-01	73.209
1979-01-01	73.602
1980-01-01	73.974
1981-01-01	74.330
1982-01-01	74.677
1983-01-01	75.020
1984-01-01	75.362
1985-01-01	75.702
1986-01-01	76.036
1987-01-01	76.363
1988-01-01	76.680
1989-01-01	76.990
1990-01-01	77.296
1991-01-01	77.607
1992-01-01	77.926
1993-01-01	78.253
1994-01-01	78.588
1995-01-01	78.925
1996-01-01	79.256
1997-01-01	79.573
1998-01-01	79.872
1999-01-01	80.150
2000-01-01	80.407
2001-01-01	80.645
2002-01-01	80.870
2003-01-01	81.089
2004-01-01	81.304
2005-01-01	81.523
2006-01-01	81.748
2007-01-01	81.981
2008-01-01	82.220
2009-01-01	82.462
2010-01-01	82.704
2011-01-01	82.937
2012-01-01	83.155
2013-01-01	83.355
2014-01-01	83.536
2015-01-01	83.700
2016-01-01	83.849