Year	Number of Years
1960-01-01	41.891
1961-01-01	42.357
1962-01-01	42.882
1963-01-01	43.478
1964-01-01	44.145
1965-01-01	44.869
1966-01-01	45.625
1967-01-01	46.384
1968-01-01	47.123
1969-01-01	47.832
1970-01-01	48.512
1971-01-01	49.175
1972-01-01	49.837
1973-01-01	50.512
1974-01-01	51.203
1975-01-01	51.916
1976-01-01	52.657
1977-01-01	53.415
1978-01-01	54.175
1979-01-01	54.920
1980-01-01	55.619
1981-01-01	56.237
1982-01-01	56.756
1983-01-01	57.172
1984-01-01	57.491
1985-01-01	57.732
1986-01-01	57.928
1987-01-01	58.117
1988-01-01	58.329
1989-01-01	58.577
1990-01-01	58.865
1991-01-01	59.182
1992-01-01	59.508
1993-01-01	59.824
1994-01-01	60.128
1995-01-01	60.418
1996-01-01	60.698
1997-01-01	60.975
1998-01-01	61.254
1999-01-01	61.538
2000-01-01	61.832
2001-01-01	62.139
2002-01-01	62.458
2003-01-01	62.784
2004-01-01	63.113
2005-01-01	63.433
2006-01-01	63.733
2007-01-01	64.006
2008-01-01	64.247
2009-01-01	64.455
2010-01-01	64.634
2011-01-01	64.791
2012-01-01	64.937
2013-01-01	65.082
2014-01-01	65.230
2015-01-01	65.384
2016-01-01	65.544