Year	Number of Years
1960-01-01	59.369
1961-01-01	59.769
1962-01-01	60.177
1963-01-01	60.611
1964-01-01	61.078
1965-01-01	61.579
1966-01-01	62.104
1967-01-01	62.631
1968-01-01	63.144
1969-01-01	63.634
1970-01-01	64.097
1971-01-01	64.528
1972-01-01	64.934
1973-01-01	65.321
1974-01-01	65.694
1975-01-01	66.067
1976-01-01	66.459
1977-01-01	66.874
1978-01-01	67.308
1979-01-01	67.751
1980-01-01	68.171
1981-01-01	68.529
1982-01-01	68.801
1983-01-01	68.975
1984-01-01	69.058
1985-01-01	69.079
1986-01-01	69.086
1987-01-01	69.121
1988-01-01	69.209
1989-01-01	69.351
1990-01-01	69.511
1991-01-01	69.628
1992-01-01	69.660
1993-01-01	69.593
1994-01-01	69.452
1995-01-01	69.310
1996-01-01	69.267
1997-01-01	69.399
1998-01-01	69.744
1999-01-01	70.296
2000-01-01	71.002
2001-01-01	71.775
2002-01-01	72.511
2003-01-01	73.128
2004-01-01	73.593
2005-01-01	73.896
2006-01-01	74.059
2007-01-01	74.144
2008-01-01	74.207
2009-01-01	74.270
2010-01-01	74.352
2011-01-01	74.462
2012-01-01	74.593
2013-01-01	74.741
2014-01-01	74.906
2015-01-01	75.088
2016-01-01	75.284