Year	Number of Years
1960-01-01	61.094
1961-01-01	61.848
1962-01-01	62.603
1963-01-01	63.356
1964-01-01	64.105
1965-01-01	64.848
1966-01-01	65.582
1967-01-01	66.302
1968-01-01	67.002
1969-01-01	67.675
1970-01-01	68.313
1971-01-01	68.910
1972-01-01	69.465
1973-01-01	69.976
1974-01-01	70.446
1975-01-01	70.877
1976-01-01	71.274
1977-01-01	71.644
1978-01-01	71.995
1979-01-01	72.329
1980-01-01	72.649
1981-01-01	72.956
1982-01-01	73.247
1983-01-01	73.520
1984-01-01	73.777
1985-01-01	74.017
1986-01-01	74.241
1987-01-01	74.448
1988-01-01	74.640
1989-01-01	74.818
1990-01-01	74.984
1991-01-01	75.138
1992-01-01	75.283
1993-01-01	75.420
1994-01-01	75.551
1995-01-01	75.678
1996-01-01	75.802
1997-01-01	75.924
1998-01-01	76.045
1999-01-01	76.164
2000-01-01	76.279
2001-01-01	76.387
2002-01-01	76.488
2003-01-01	76.581
2004-01-01	76.668
2005-01-01	76.754
2006-01-01	76.843
2007-01-01	76.940
2008-01-01	77.049
2009-01-01	77.169
2010-01-01	77.301
2011-01-01	77.443
2012-01-01	77.590
2013-01-01	77.739
2014-01-01	77.888
2015-01-01	78.036
2016-01-01	78.184