Year	Number of Years
1960-01-01	37.854
1961-01-01	38.157
1962-01-01	38.481
1963-01-01	38.828
1964-01-01	39.195
1965-01-01	39.580
1966-01-01	39.975
1967-01-01	40.372
1968-01-01	40.767
1969-01-01	41.155
1970-01-01	41.538
1971-01-01	41.917
1972-01-01	42.295
1973-01-01	42.679
1974-01-01	43.068
1975-01-01	43.465
1976-01-01	43.873
1977-01-01	44.292
1978-01-01	44.717
1979-01-01	45.146
1980-01-01	45.569
1981-01-01	45.979
1982-01-01	46.369
1983-01-01	46.737
1984-01-01	47.084
1985-01-01	47.414
1986-01-01	47.734
1987-01-01	48.054
1988-01-01	48.381
1989-01-01	48.718
1990-01-01	49.071
1991-01-01	49.441
1992-01-01	49.825
1993-01-01	50.213
1994-01-01	50.599
1995-01-01	50.969
1996-01-01	51.306
1997-01-01	51.604
1998-01-01	51.860
1999-01-01	52.079
2000-01-01	52.270
2001-01-01	52.450
2002-01-01	52.636
2003-01-01	52.845
2004-01-01	53.084
2005-01-01	53.357
2006-01-01	53.663
2007-01-01	53.991
2008-01-01	54.333
2009-01-01	54.687
2010-01-01	55.050
2011-01-01	55.424
2012-01-01	55.807
2013-01-01	56.200
2014-01-01	56.598
2015-01-01	57.000
2016-01-01	57.403