Year	Number of Years
1960-01-01	57.580
1961-01-01	57.980
1962-01-01	58.379
1963-01-01	58.777
1964-01-01	59.176
1965-01-01	59.576
1966-01-01	59.979
1967-01-01	60.386
1968-01-01	60.797
1969-01-01	61.211
1970-01-01	61.634
1971-01-01	62.071
1972-01-01	62.519
1973-01-01	62.971
1974-01-01	63.419
1975-01-01	63.843
1976-01-01	64.225
1977-01-01	64.552
1978-01-01	64.817
1979-01-01	65.021
1980-01-01	65.171
1981-01-01	65.280
1982-01-01	65.368
1983-01-01	65.452
1984-01-01	65.541
1985-01-01	65.641
1986-01-01	65.752
1987-01-01	65.868
1988-01-01	65.983
1989-01-01	66.098
1990-01-01	66.212
1991-01-01	66.325
1992-01-01	66.439
1993-01-01	66.552
1994-01-01	66.665
1995-01-01	66.776
1996-01-01	66.884
1997-01-01	66.990
1998-01-01	67.092
1999-01-01	67.195
2000-01-01	67.300
2001-01-01	67.414
2002-01-01	67.539
2003-01-01	67.675
2004-01-01	67.820
2005-01-01	67.969
2006-01-01	68.115
2007-01-01	68.251
2008-01-01	68.375
2009-01-01	68.484
2010-01-01	68.582
2011-01-01	68.673
2012-01-01	68.765
2013-01-01	68.862
2014-01-01	68.966
2015-01-01	69.078
2016-01-01	69.195