Year	Number of Years
1960-01-01	65.662
1961-01-01	66.074
1962-01-01	66.444
1963-01-01	66.787
1964-01-01	67.113
1965-01-01	67.435
1966-01-01	67.762
1967-01-01	68.095
1968-01-01	68.436
1969-01-01	68.784
1970-01-01	69.140
1971-01-01	69.498
1972-01-01	69.851
1973-01-01	70.191
1974-01-01	70.519
1975-01-01	70.833
1976-01-01	71.140
1977-01-01	71.441
1978-01-01	71.736
1979-01-01	72.023
1980-01-01	72.293
1981-01-01	72.538
1982-01-01	72.751
1983-01-01	72.929
1984-01-01	73.071
1985-01-01	73.181
1986-01-01	73.262
1987-01-01	73.325
1988-01-01	73.378
1989-01-01	73.425
1990-01-01	73.468
1991-01-01	73.509
1992-01-01	73.544
1993-01-01	73.573
1994-01-01	73.598
1995-01-01	73.622
1996-01-01	73.646
1997-01-01	73.671
1998-01-01	73.700
1999-01-01	73.738
2000-01-01	73.787
2001-01-01	73.853
2002-01-01	73.937
2003-01-01	74.038
2004-01-01	74.156
2005-01-01	74.287
2006-01-01	74.429
2007-01-01	74.576
2008-01-01	74.725
2009-01-01	74.872
2010-01-01	75.016
2011-01-01	75.158
2012-01-01	75.299
2013-01-01	75.440
2014-01-01	75.582
2015-01-01	75.725
2016-01-01	75.867