Year	Number of Years
1960-01-01	38.019
1961-01-01	38.279
1962-01-01	38.536
1963-01-01	38.795
1964-01-01	39.061
1965-01-01	39.346
1966-01-01	39.666
1967-01-01	40.028
1968-01-01	40.432
1969-01-01	40.872
1970-01-01	41.332
1971-01-01	41.792
1972-01-01	42.233
1973-01-01	42.638
1974-01-01	43.003
1975-01-01	43.327
1976-01-01	43.619
1977-01-01	43.892
1978-01-01	44.161
1979-01-01	44.430
1980-01-01	44.704
1981-01-01	44.986
1982-01-01	45.269
1983-01-01	45.550
1984-01-01	45.824
1985-01-01	46.082
1986-01-01	46.315
1987-01-01	46.520
1988-01-01	46.692
1989-01-01	46.835
1990-01-01	46.952
1991-01-01	47.053
1992-01-01	47.148
1993-01-01	47.243
1994-01-01	47.339
1995-01-01	47.431
1996-01-01	47.505
1997-01-01	47.556
1998-01-01	47.582
1999-01-01	47.590
2000-01-01	47.593
2001-01-01	47.603
2002-01-01	47.638
2003-01-01	47.716
2004-01-01	47.848
2005-01-01	48.054
2006-01-01	48.349
2007-01-01	48.729
2008-01-01	49.182
2009-01-01	49.691
2010-01-01	50.233
2011-01-01	50.778
2012-01-01	51.300
2013-01-01	51.778
2014-01-01	52.204
2015-01-01	52.575
2016-01-01	52.903