Year	Number of Years
1960-01-01	58.835
1961-01-01	59.210
1962-01-01	59.588
1963-01-01	59.968
1964-01-01	60.347
1965-01-01	60.721
1966-01-01	61.087
1967-01-01	61.441
1968-01-01	61.778
1969-01-01	62.097
1970-01-01	62.391
1971-01-01	62.659
1972-01-01	62.902
1973-01-01	63.125
1974-01-01	63.331
1975-01-01	63.530
1976-01-01	63.728
1977-01-01	63.934
1978-01-01	64.152
1979-01-01	64.384
1980-01-01	64.637
1981-01-01	64.913
1982-01-01	65.206
1983-01-01	65.504
1984-01-01	65.795
1985-01-01	66.058
1986-01-01	66.269
1987-01-01	66.415
1988-01-01	66.495
1989-01-01	66.512
1990-01-01	66.481
1991-01-01	66.424
1992-01-01	66.368
1993-01-01	66.336
1994-01-01	66.343
1995-01-01	66.396
1996-01-01	66.494
1997-01-01	66.626
1998-01-01	66.782
1999-01-01	66.959
2000-01-01	67.154
2001-01-01	67.366
2002-01-01	67.594
2003-01-01	67.837
2004-01-01	68.094
2005-01-01	68.367
2006-01-01	68.663
2007-01-01	68.982
2008-01-01	69.319
2009-01-01	69.665
2010-01-01	70.005
2011-01-01	70.322
2012-01-01	70.604
2013-01-01	70.844
2014-01-01	71.039
2015-01-01	71.192
2016-01-01	71.314