Year	Number of Years
1960-01-01	41.098
1961-01-01	41.312
1962-01-01	41.529
1963-01-01	41.755
1964-01-01	41.995
1965-01-01	42.257
1966-01-01	42.549
1967-01-01	42.868
1968-01-01	43.208
1969-01-01	43.563
1970-01-01	43.915
1971-01-01	44.247
1972-01-01	44.545
1973-01-01	44.804
1974-01-01	45.026
1975-01-01	45.222
1976-01-01	45.410
1977-01-01	45.609
1978-01-01	45.833
1979-01-01	46.086
1980-01-01	46.363
1981-01-01	46.651
1982-01-01	46.937
1983-01-01	47.208
1984-01-01	47.461
1985-01-01	47.705
1986-01-01	47.955
1987-01-01	48.221
1988-01-01	48.502
1989-01-01	48.787
1990-01-01	49.043
1991-01-01	49.225
1992-01-01	49.311
1993-01-01	49.302
1994-01-01	49.220
1995-01-01	49.111
1996-01-01	49.040
1997-01-01	49.066
1998-01-01	49.233
1999-01-01	49.557
2000-01-01	50.041
2001-01-01	50.667
2002-01-01	51.385
2003-01-01	52.144
2004-01-01	52.917
2005-01-01	53.675
2006-01-01	54.401
2007-01-01	55.091
2008-01-01	55.743
2009-01-01	56.350
2010-01-01	56.907
2011-01-01	57.418
2012-01-01	57.894
2013-01-01	58.347
2014-01-01	58.782
2015-01-01	59.205
2016-01-01	59.621