Year	Number of Years
1960-01-01	57.329
1961-01-01	58.130
1962-01-01	58.872
1963-01-01	59.531
1964-01-01	60.104
1965-01-01	60.602
1966-01-01	61.052
1967-01-01	61.494
1968-01-01	61.962
1969-01-01	62.468
1970-01-01	63.017
1971-01-01	63.604
1972-01-01	64.210
1973-01-01	64.818
1974-01-01	65.422
1975-01-01	66.020
1976-01-01	66.615
1977-01-01	67.207
1978-01-01	67.791
1979-01-01	68.354
1980-01-01	68.880
1981-01-01	69.348
1982-01-01	69.747
1983-01-01	70.074
1984-01-01	70.329
1985-01-01	70.521
1986-01-01	70.668
1987-01-01	70.789
1988-01-01	70.900
1989-01-01	71.008
1990-01-01	71.108
1991-01-01	71.187
1992-01-01	71.235
1993-01-01	71.248
1994-01-01	71.235
1995-01-01	71.209
1996-01-01	71.186
1997-01-01	71.184
1998-01-01	71.221
1999-01-01	71.307
2000-01-01	71.456
2001-01-01	71.676
2002-01-01	71.958
2003-01-01	72.287
2004-01-01	72.652
2005-01-01	73.028
2006-01-01	73.393
2007-01-01	73.728
2008-01-01	74.020
2009-01-01	74.265
2010-01-01	74.465
2011-01-01	74.633
2012-01-01	74.788
2013-01-01	74.947
2014-01-01	75.117
2015-01-01	75.300
2016-01-01	75.496