Year	Number of Years
1960-01-01	61.401
1961-01-01	61.767
1962-01-01	62.130
1963-01-01	62.488
1964-01-01	62.840
1965-01-01	63.188
1966-01-01	63.533
1967-01-01	63.876
1968-01-01	64.215
1969-01-01	64.550
1970-01-01	64.876
1971-01-01	65.189
1972-01-01	65.486
1973-01-01	65.766
1974-01-01	66.030
1975-01-01	66.280
1976-01-01	66.521
1977-01-01	66.757
1978-01-01	66.994
1979-01-01	67.232
1980-01-01	67.476
1981-01-01	67.725
1982-01-01	67.978
1983-01-01	68.230
1984-01-01	68.478
1985-01-01	68.716
1986-01-01	68.936
1987-01-01	69.136
1988-01-01	69.313
1989-01-01	69.468
1990-01-01	69.603
1991-01-01	69.722
1992-01-01	69.832
1993-01-01	69.940
1994-01-01	70.050
1995-01-01	70.164
1996-01-01	70.285
1997-01-01	70.411
1998-01-01	70.541
1999-01-01	70.674
2000-01-01	70.811
2001-01-01	70.949
2002-01-01	71.089
2003-01-01	71.229
2004-01-01	71.367
2005-01-01	71.504
2006-01-01	71.639
2007-01-01	71.773
2008-01-01	71.906
2009-01-01	72.039
2010-01-01	72.173
2011-01-01	72.308
2012-01-01	72.446
2013-01-01	72.588
2014-01-01	72.732
2015-01-01	72.880
2016-01-01	73.029