Year	Number of Years
1960-01-01	61.035
1961-01-01	61.257
1962-01-01	61.470
1963-01-01	61.679
1964-01-01	61.890
1965-01-01	62.104
1966-01-01	62.322
1967-01-01	62.539
1968-01-01	62.751
1969-01-01	62.953
1970-01-01	63.141
1971-01-01	63.310
1972-01-01	63.457
1973-01-01	63.583
1974-01-01	63.688
1975-01-01	63.776
1976-01-01	63.852
1977-01-01	63.922
1978-01-01	63.992
1979-01-01	64.069
1980-01-01	64.161
1981-01-01	64.280
1982-01-01	64.424
1983-01-01	64.587
1984-01-01	64.759
1985-01-01	64.913
1986-01-01	65.016
1987-01-01	65.053
1988-01-01	65.021
1989-01-01	64.935
1990-01-01	64.827
1991-01-01	64.745
1992-01-01	64.731
1993-01-01	64.810
1994-01-01	64.991
1995-01-01	65.256
1996-01-01	65.573
1997-01-01	65.899
1998-01-01	66.207
1999-01-01	66.491
2000-01-01	66.763
2001-01-01	67.054
2002-01-01	67.391
2003-01-01	67.791
2004-01-01	68.249
2005-01-01	68.750
2006-01-01	69.269
2007-01-01	69.774
2008-01-01	70.238
2009-01-01	70.646
2010-01-01	70.987
2011-01-01	71.260
2012-01-01	71.478
2013-01-01	71.656
2014-01-01	71.800
2015-01-01	71.921
2016-01-01	72.026