Year	Number of Years
1960-01-01	39.962
1961-01-01	40.444
1962-01-01	40.924
1963-01-01	41.401
1964-01-01	41.876
1965-01-01	42.351
1966-01-01	42.828
1967-01-01	43.310
1968-01-01	43.796
1969-01-01	44.283
1970-01-01	44.771
1971-01-01	45.257
1972-01-01	45.735
1973-01-01	46.203
1974-01-01	46.656
1975-01-01	47.094
1976-01-01	47.517
1977-01-01	47.926
1978-01-01	48.317
1979-01-01	48.683
1980-01-01	49.005
1981-01-01	49.260
1982-01-01	49.442
1983-01-01	49.560
1984-01-01	49.634
1985-01-01	49.694
1986-01-01	49.781
1987-01-01	49.932
1988-01-01	50.176
1989-01-01	50.530
1990-01-01	51.003
1991-01-01	51.595
1992-01-01	52.278
1993-01-01	53.022
1994-01-01	53.808
1995-01-01	54.616
1996-01-01	55.430
1997-01-01	56.239
1998-01-01	57.028
1999-01-01	57.782
2000-01-01	58.485
2001-01-01	59.129
2002-01-01	59.717
2003-01-01	60.256
2004-01-01	60.752
2005-01-01	61.212
2006-01-01	61.650
2007-01-01	62.079
2008-01-01	62.509
2009-01-01	62.944
2010-01-01	63.388
2011-01-01	63.836
2012-01-01	64.280
2013-01-01	64.713
2014-01-01	65.133
2015-01-01	65.539
2016-01-01	65.932