Year	Number of Years
1960-01-01	35.197
1961-01-01	35.561
1962-01-01	35.981
1963-01-01	36.455
1964-01-01	36.976
1965-01-01	37.537
1966-01-01	38.125
1967-01-01	38.729
1968-01-01	39.339
1969-01-01	39.946
1970-01-01	40.544
1971-01-01	41.129
1972-01-01	41.706
1973-01-01	42.280
1974-01-01	42.855
1975-01-01	43.434
1976-01-01	44.023
1977-01-01	44.627
1978-01-01	45.250
1979-01-01	45.895
1980-01-01	46.562
1981-01-01	47.249
1982-01-01	47.954
1983-01-01	48.673
1984-01-01	49.408
1985-01-01	50.162
1986-01-01	50.938
1987-01-01	51.738
1988-01-01	52.561
1989-01-01	53.403
1990-01-01	54.260
1991-01-01	55.125
1992-01-01	55.992
1993-01-01	56.852
1994-01-01	57.699
1995-01-01	58.529
1996-01-01	59.341
1997-01-01	60.134
1998-01-01	60.909
1999-01-01	61.661
2000-01-01	62.386
2001-01-01	63.082
2002-01-01	63.745
2003-01-01	64.376
2004-01-01	64.973
2005-01-01	65.537
2006-01-01	66.066
2007-01-01	66.565
2008-01-01	67.036
2009-01-01	67.484
2010-01-01	67.914
2011-01-01	68.329
2012-01-01	68.732
2013-01-01	69.126
2014-01-01	69.511
2015-01-01	69.887
2016-01-01	70.253