Year	Number of Years
1960-01-01	70.739
1961-01-01	70.833
1962-01-01	70.928
1963-01-01	71.030
1964-01-01	71.143
1965-01-01	71.265
1966-01-01	71.391
1967-01-01	71.512
1968-01-01	71.623
1969-01-01	71.726
1970-01-01	71.823
1971-01-01	71.919
1972-01-01	72.020
1973-01-01	72.133
1974-01-01	72.261
1975-01-01	72.409
1976-01-01	72.580
1977-01-01	72.773
1978-01-01	72.983
1979-01-01	73.208
1980-01-01	73.439
1981-01-01	73.668
1982-01-01	73.890
1983-01-01	74.101
1984-01-01	74.300
1985-01-01	74.490
1986-01-01	74.678
1987-01-01	74.871
1988-01-01	75.074
1989-01-01	75.287
1990-01-01	75.507
1991-01-01	75.726
1992-01-01	75.940
1993-01-01	76.143
1994-01-01	76.338
1995-01-01	76.528
1996-01-01	76.719
1997-01-01	76.918
1998-01-01	77.130
1999-01-01	77.358
2000-01-01	77.602
2001-01-01	77.864
2002-01-01	78.137
2003-01-01	78.417
2004-01-01	78.699
2005-01-01	78.975
2006-01-01	79.241
2007-01-01	79.493
2008-01-01	79.729
2009-01-01	79.947
2010-01-01	80.145
2011-01-01	80.326
2012-01-01	80.494
2013-01-01	80.654
2014-01-01	80.807
2015-01-01	80.958
2016-01-01	81.107