Year	Number of Years
1960-01-01	40.297
1961-01-01	40.941
1962-01-01	41.580
1963-01-01	42.215
1964-01-01	42.846
1965-01-01	43.473
1966-01-01	44.098
1967-01-01	44.720
1968-01-01	45.339
1969-01-01	45.955
1970-01-01	46.568
1971-01-01	47.175
1972-01-01	47.777
1973-01-01	48.371
1974-01-01	48.958
1975-01-01	49.537
1976-01-01	50.112
1977-01-01	50.683
1978-01-01	51.246
1979-01-01	51.799
1980-01-01	52.339
1981-01-01	52.863
1982-01-01	53.365
1983-01-01	53.839
1984-01-01	54.276
1985-01-01	54.673
1986-01-01	55.028
1987-01-01	55.337
1988-01-01	55.592
1989-01-01	55.784
1990-01-01	55.888
1991-01-01	55.873
1992-01-01	55.734
1993-01-01	55.485
1994-01-01	55.146
1995-01-01	54.756
1996-01-01	54.359
1997-01-01	54.000
1998-01-01	53.720
1999-01-01	53.544
2000-01-01	53.489
2001-01-01	53.551
2002-01-01	53.707
2003-01-01	53.935
2004-01-01	54.230
2005-01-01	54.598
2006-01-01	55.048
2007-01-01	55.578
2008-01-01	56.174
2009-01-01	56.814
2010-01-01	57.465
2011-01-01	58.092
2012-01-01	58.668
2013-01-01	59.174
2014-01-01	59.601
2015-01-01	59.949
2016-01-01	60.232