Year	Number of Years
1960-01-01	63.267
1961-01-01	63.575
1962-01-01	63.871
1963-01-01	64.157
1964-01-01	64.435
1965-01-01	64.709
1966-01-01	64.982
1967-01-01	65.255
1968-01-01	65.528
1969-01-01	65.800
1970-01-01	66.067
1971-01-01	66.323
1972-01-01	66.565
1973-01-01	66.789
1974-01-01	66.995
1975-01-01	67.183
1976-01-01	67.352
1977-01-01	67.508
1978-01-01	67.657
1979-01-01	67.804
1980-01-01	67.955
1981-01-01	68.115
1982-01-01	68.287
1983-01-01	68.475
1984-01-01	68.681
1985-01-01	68.904
1986-01-01	69.143
1987-01-01	69.394
1988-01-01	69.656
1989-01-01	69.930
1990-01-01	70.222
1991-01-01	70.537
1992-01-01	70.878
1993-01-01	71.248
1994-01-01	71.646
1995-01-01	72.071
1996-01-01	72.522
1997-01-01	72.991
1998-01-01	73.473
1999-01-01	73.959
2000-01-01	74.447
2001-01-01	74.934
2002-01-01	75.418
2003-01-01	75.892
2004-01-01	76.351
2005-01-01	76.786
2006-01-01	77.187
2007-01-01	77.553
2008-01-01	77.881
2009-01-01	78.173
2010-01-01	78.430
2011-01-01	78.656
2012-01-01	78.860
2013-01-01	79.050
2014-01-01	79.231
2015-01-01	79.409
2016-01-01	79.584