Year	Number of Years
1960-01-01	57.285
1961-01-01	57.682
1962-01-01	58.097
1963-01-01	58.533
1964-01-01	58.993
1965-01-01	59.479
1966-01-01	59.994
1967-01-01	60.536
1968-01-01	61.104
1969-01-01	61.696
1970-01-01	62.311
1971-01-01	62.950
1972-01-01	63.609
1973-01-01	64.283
1974-01-01	64.967
1975-01-01	65.658
1976-01-01	66.355
1977-01-01	67.052
1978-01-01	67.744
1979-01-01	68.422
1980-01-01	69.074
1981-01-01	69.690
1982-01-01	70.265
1983-01-01	70.798
1984-01-01	71.288
1985-01-01	71.739
1986-01-01	72.157
1987-01-01	72.553
1988-01-01	72.936
1989-01-01	73.311
1990-01-01	73.680
1991-01-01	74.042
1992-01-01	74.394
1993-01-01	74.733
1994-01-01	75.059
1995-01-01	75.374
1996-01-01	75.678
1997-01-01	75.974
1998-01-01	76.259
1999-01-01	76.533
2000-01-01	76.793
2001-01-01	77.034
2002-01-01	77.255
2003-01-01	77.453
2004-01-01	77.632
2005-01-01	77.791
2006-01-01	77.934
2007-01-01	78.066
2008-01-01	78.193
2009-01-01	78.320
2010-01-01	78.454
2011-01-01	78.599
2012-01-01	78.758
2013-01-01	78.931
2014-01-01	79.117
2015-01-01	79.315
2016-01-01	79.522