Year	Number of Years
1960-01-01	59.466
1961-01-01	60.044
1962-01-01	60.605
1963-01-01	61.148
1964-01-01	61.672
1965-01-01	62.176
1966-01-01	62.661
1967-01-01	63.128
1968-01-01	63.581
1969-01-01	64.019
1970-01-01	64.445
1971-01-01	64.857
1972-01-01	65.256
1973-01-01	65.643
1974-01-01	66.019
1975-01-01	66.383
1976-01-01	66.736
1977-01-01	67.078
1978-01-01	67.410
1979-01-01	67.732
1980-01-01	68.044
1981-01-01	68.348
1982-01-01	68.643
1983-01-01	68.930
1984-01-01	69.210
1985-01-01	69.482
1986-01-01	69.746
1987-01-01	70.002
1988-01-01	70.251
1989-01-01	70.492
1990-01-01	70.727
1991-01-01	70.955
1992-01-01	71.177
1993-01-01	71.394
1994-01-01	71.605
1995-01-01	71.813
1996-01-01	72.019
1997-01-01	72.222
1998-01-01	72.422
1999-01-01	72.616
2000-01-01	72.800
2001-01-01	72.966
2002-01-01	73.113
2003-01-01	73.242
2004-01-01	73.356
2005-01-01	73.463
2006-01-01	73.577
2007-01-01	73.704
2008-01-01	73.852
2009-01-01	74.022
2010-01-01	74.210
2011-01-01	74.408
2012-01-01	74.606
2013-01-01	74.797
2014-01-01	74.976
2015-01-01	75.143
2016-01-01	75.300