Year	Number of Years
1960-01-01	43.991
1961-01-01	44.568
1962-01-01	45.156
1963-01-01	45.748
1964-01-01	46.332
1965-01-01	46.891
1966-01-01	47.407
1967-01-01	47.865
1968-01-01	48.258
1969-01-01	48.578
1970-01-01	48.827
1971-01-01	49.010
1972-01-01	49.142
1973-01-01	49.236
1974-01-01	49.301
1975-01-01	49.347
1976-01-01	49.384
1977-01-01	49.412
1978-01-01	49.426
1979-01-01	49.419
1980-01-01	49.374
1981-01-01	49.272
1982-01-01	49.096
1983-01-01	48.842
1984-01-01	48.512
1985-01-01	48.104
1986-01-01	47.625
1987-01-01	47.097
1988-01-01	46.549
1989-01-01	46.012
1990-01-01	45.509
1991-01-01	45.058
1992-01-01	44.676
1993-01-01	44.388
1994-01-01	44.223
1995-01-01	44.220
1996-01-01	44.415
1997-01-01	44.811
1998-01-01	45.397
1999-01-01	46.160
2000-01-01	47.077
2001-01-01	48.120
2002-01-01	49.242
2003-01-01	50.394
2004-01-01	51.538
2005-01-01	52.640
2006-01-01	53.681
2007-01-01	54.660
2008-01-01	55.574
2009-01-01	56.409
2010-01-01	57.153
2011-01-01	57.796
2012-01-01	58.347
2013-01-01	58.819
2014-01-01	59.224
2015-01-01	59.575
2016-01-01	59.889