Year	Number of Years
1960-01-01	62.467
1961-01-01	63.017
1962-01-01	63.544
1963-01-01	64.044
1964-01-01	64.515
1965-01-01	64.957
1966-01-01	65.375
1967-01-01	65.776
1968-01-01	66.167
1969-01-01	66.550
1970-01-01	66.928
1971-01-01	67.300
1972-01-01	67.665
1973-01-01	68.021
1974-01-01	68.369
1975-01-01	68.706
1976-01-01	69.032
1977-01-01	69.347
1978-01-01	69.651
1979-01-01	69.945
1980-01-01	70.230
1981-01-01	70.509
1982-01-01	70.784
1983-01-01	71.056
1984-01-01	71.326
1985-01-01	71.595
1986-01-01	71.864
1987-01-01	72.132
1988-01-01	72.397
1989-01-01	72.659
1990-01-01	72.916
1991-01-01	73.167
1992-01-01	73.413
1993-01-01	73.651
1994-01-01	73.883
1995-01-01	74.110
1996-01-01	74.332
1997-01-01	74.551
1998-01-01	74.769
1999-01-01	74.985
2000-01-01	75.202
2001-01-01	75.425
2002-01-01	75.650
2003-01-01	75.875
2004-01-01	76.093
2005-01-01	76.291
2006-01-01	76.455
2007-01-01	76.577
2008-01-01	76.656
2009-01-01	76.699
2010-01-01	76.719
2011-01-01	76.734
2012-01-01	76.764
2013-01-01	76.823
2014-01-01	76.917
2015-01-01	77.046
2016-01-01	77.203