Year	Number of Years
1960-01-01	48.194
1961-01-01	48.618
1962-01-01	49.035
1963-01-01	49.446
1964-01-01	49.852
1965-01-01	50.257
1966-01-01	50.663
1967-01-01	51.069
1968-01-01	51.469
1969-01-01	51.860
1970-01-01	52.234
1971-01-01	52.583
1972-01-01	52.901
1973-01-01	53.184
1974-01-01	53.430
1975-01-01	53.638
1976-01-01	53.807
1977-01-01	53.946
1978-01-01	54.061
1979-01-01	54.161
1980-01-01	54.253
1981-01-01	54.342
1982-01-01	54.435
1983-01-01	54.534
1984-01-01	54.645
1985-01-01	54.768
1986-01-01	54.901
1987-01-01	55.039
1988-01-01	55.182
1989-01-01	55.334
1990-01-01	55.500
1991-01-01	55.688
1992-01-01	55.902
1993-01-01	56.145
1994-01-01	56.417
1995-01-01	56.716
1996-01-01	57.036
1997-01-01	57.372
1998-01-01	57.718
1999-01-01	58.070
2000-01-01	58.430
2001-01-01	58.801
2002-01-01	59.184
2003-01-01	59.582
2004-01-01	59.993
2005-01-01	60.416
2006-01-01	60.854
2007-01-01	61.300
2008-01-01	61.749
2009-01-01	62.193
2010-01-01	62.620
2011-01-01	63.019
2012-01-01	63.384
2013-01-01	63.712
2014-01-01	64.002
2015-01-01	64.257
2016-01-01	64.486