Year	Number of Years
1960-01-01	60.353
1961-01-01	61.019
1962-01-01	61.646
1963-01-01	62.243
1964-01-01	62.818
1965-01-01	63.381
1966-01-01	63.940
1967-01-01	64.499
1968-01-01	65.059
1969-01-01	65.621
1970-01-01	66.187
1971-01-01	66.756
1972-01-01	67.320
1973-01-01	67.867
1974-01-01	68.390
1975-01-01	68.872
1976-01-01	69.296
1977-01-01	69.657
1978-01-01	69.954
1979-01-01	70.193
1980-01-01	70.399
1981-01-01	70.601
1982-01-01	70.820
1983-01-01	71.061
1984-01-01	71.315
1985-01-01	71.534
1986-01-01	71.650
1987-01-01	71.626
1988-01-01	71.461
1989-01-01	71.185
1990-01-01	70.877
1991-01-01	70.645
1992-01-01	70.577
1993-01-01	70.724
1994-01-01	71.091
1995-01-01	71.643
1996-01-01	72.306
1997-01-01	72.977
1998-01-01	73.572
1999-01-01	74.057
2000-01-01	74.413
2001-01-01	74.653
2002-01-01	74.824
2003-01-01	74.967
2004-01-01	75.096
2005-01-01	75.223
2006-01-01	75.353
2007-01-01	75.486
2008-01-01	75.619
2009-01-01	75.758
2010-01-01	75.905
2011-01-01	76.060
2012-01-01	76.223
2013-01-01	76.390
2014-01-01	76.561
2015-01-01	76.735
2016-01-01	76.911