Year	Number of Years
1960-01-01	38.223
1961-01-01	38.380
1962-01-01	38.462
1963-01-01	38.477
1964-01-01	38.449
1965-01-01	38.407
1966-01-01	38.386
1967-01-01	38.424
1968-01-01	38.558
1969-01-01	38.816
1970-01-01	39.227
1971-01-01	39.814
1972-01-01	40.562
1973-01-01	41.445
1974-01-01	42.442
1975-01-01	43.521
1976-01-01	44.641
1977-01-01	45.767
1978-01-01	46.869
1979-01-01	47.927
1980-01-01	48.944
1981-01-01	49.940
1982-01-01	50.938
1983-01-01	51.945
1984-01-01	52.946
1985-01-01	53.914
1986-01-01	54.813
1987-01-01	55.610
1988-01-01	56.283
1989-01-01	56.818
1990-01-01	57.202
1991-01-01	57.430
1992-01-01	57.529
1993-01-01	57.535
1994-01-01	57.480
1995-01-01	57.405
1996-01-01	57.344
1997-01-01	57.328
1998-01-01	57.383
1999-01-01	57.533
2000-01-01	57.796
2001-01-01	58.180
2002-01-01	58.665
2003-01-01	59.230
2004-01-01	59.859
2005-01-01	60.541
2006-01-01	61.263
2007-01-01	62.008
2008-01-01	62.755
2009-01-01	63.485
2010-01-01	64.177
2011-01-01	64.814
2012-01-01	65.393
2013-01-01	65.914
2014-01-01	66.376
2015-01-01	66.784
2016-01-01	67.146