Year	Number of Years
1960-01-01	36.865
1961-01-01	37.554
1962-01-01	38.223
1963-01-01	38.866
1964-01-01	39.488
1965-01-01	40.103
1966-01-01	40.736
1967-01-01	41.406
1968-01-01	42.125
1969-01-01	42.890
1970-01-01	43.695
1971-01-01	44.526
1972-01-01	45.357
1973-01-01	46.166
1974-01-01	46.940
1975-01-01	47.668
1976-01-01	48.346
1977-01-01	48.979
1978-01-01	49.570
1979-01-01	50.115
1980-01-01	50.616
1981-01-01	51.079
1982-01-01	51.503
1983-01-01	51.885
1984-01-01	52.215
1985-01-01	52.484
1986-01-01	52.677
1987-01-01	52.786
1988-01-01	52.798
1989-01-01	52.706
1990-01-01	52.486
1991-01-01	52.117
1992-01-01	51.605
1993-01-01	50.975
1994-01-01	50.259
1995-01-01	49.501
1996-01-01	48.746
1997-01-01	48.043
1998-01-01	47.438
1999-01-01	46.969
2000-01-01	46.672
2001-01-01	46.567
2002-01-01	46.637
2003-01-01	46.856
2004-01-01	47.205
2005-01-01	47.658
2006-01-01	48.183
2007-01-01	48.747
2008-01-01	49.321
2009-01-01	49.883
2010-01-01	50.423
2011-01-01	50.945
2012-01-01	51.463
2013-01-01	51.989
2014-01-01	52.520
2015-01-01	53.053
2016-01-01	53.582