Year	Number of Years
1960-01-01	61.002
1961-01-01	61.481
1962-01-01	61.964
1963-01-01	62.451
1964-01-01	62.940
1965-01-01	63.426
1966-01-01	63.900
1967-01-01	64.355
1968-01-01	64.786
1969-01-01	65.191
1970-01-01	65.569
1971-01-01	65.922
1972-01-01	66.257
1973-01-01	66.580
1974-01-01	66.894
1975-01-01	67.203
1976-01-01	67.510
1977-01-01	67.816
1978-01-01	68.120
1979-01-01	68.424
1980-01-01	68.726
1981-01-01	69.024
1982-01-01	69.317
1983-01-01	69.602
1984-01-01	69.878
1985-01-01	70.145
1986-01-01	70.405
1987-01-01	70.658
1988-01-01	70.905
1989-01-01	71.147
1990-01-01	71.383
1991-01-01	71.614
1992-01-01	71.841
1993-01-01	72.061
1994-01-01	72.275
1995-01-01	72.481
1996-01-01	72.678
1997-01-01	72.865
1998-01-01	73.043
1999-01-01	73.213
2000-01-01	73.377
2001-01-01	73.535
2002-01-01	73.691
2003-01-01	73.847
2004-01-01	74.004
2005-01-01	74.163
2006-01-01	74.324
2007-01-01	74.486
2008-01-01	74.648
2009-01-01	74.811
2010-01-01	74.973
2011-01-01	75.133
2012-01-01	75.292
2013-01-01	75.448
2014-01-01	75.603
2015-01-01	75.755
2016-01-01	75.906