Year	Number of Years
1960-01-01	42.672
1961-01-01	43.499
1962-01-01	44.311
1963-01-01	45.110
1964-01-01	45.896
1965-01-01	46.665
1966-01-01	47.413
1967-01-01	48.141
1968-01-01	48.858
1969-01-01	49.574
1970-01-01	50.310
1971-01-01	51.087
1972-01-01	51.920
1973-01-01	52.811
1974-01-01	53.760
1975-01-01	54.755
1976-01-01	55.781
1977-01-01	56.813
1978-01-01	57.829
1979-01-01	58.813
1980-01-01	59.758
1981-01-01	60.659
1982-01-01	61.523
1983-01-01	62.355
1984-01-01	63.153
1985-01-01	63.915
1986-01-01	64.638
1987-01-01	65.324
1988-01-01	65.975
1989-01-01	66.593
1990-01-01	67.181
1991-01-01	67.740
1992-01-01	68.274
1993-01-01	68.787
1994-01-01	69.284
1995-01-01	69.771
1996-01-01	70.251
1997-01-01	70.726
1998-01-01	71.198
1999-01-01	71.664
2000-01-01	72.126
2001-01-01	72.580
2002-01-01	73.022
2003-01-01	73.447
2004-01-01	73.851
2005-01-01	74.231
2006-01-01	74.580
2007-01-01	74.898
2008-01-01	75.188
2009-01-01	75.451
2010-01-01	75.694
2011-01-01	75.922
2012-01-01	76.141
2013-01-01	76.358
2014-01-01	76.578
2015-01-01	76.801
2016-01-01	77.029