Year	Number of Years
1960-01-01	60.633
1961-01-01	61.259
1962-01-01	61.870
1963-01-01	62.469
1964-01-01	63.060
1965-01-01	63.642
1966-01-01	64.216
1967-01-01	64.775
1968-01-01	65.313
1969-01-01	65.824
1970-01-01	66.301
1971-01-01	66.736
1972-01-01	67.128
1973-01-01	67.474
1974-01-01	67.773
1975-01-01	68.020
1976-01-01	68.212
1977-01-01	68.355
1978-01-01	68.462
1979-01-01	68.549
1980-01-01	68.640
1981-01-01	68.764
1982-01-01	68.936
1983-01-01	69.162
1984-01-01	69.442
1985-01-01	69.760
1986-01-01	70.094
1987-01-01	70.414
1988-01-01	70.700
1989-01-01	70.945
1990-01-01	71.152
1991-01-01	71.331
1992-01-01	71.502
1993-01-01	71.680
1994-01-01	71.871
1995-01-01	72.080
1996-01-01	72.309
1997-01-01	72.550
1998-01-01	72.795
1999-01-01	73.038
2000-01-01	73.267
2001-01-01	73.470
2002-01-01	73.642
2003-01-01	73.782
2004-01-01	73.893
2005-01-01	73.986
2006-01-01	74.077
2007-01-01	74.180
2008-01-01	74.305
2009-01-01	74.457
2010-01-01	74.632
2011-01-01	74.824
2012-01-01	75.019
2013-01-01	75.207
2014-01-01	75.384
2015-01-01	75.549
2016-01-01	75.703