Year	Number of Years
1960-01-01	32.292
1961-01-01	32.742
1962-01-01	33.185
1963-01-01	33.624
1964-01-01	34.060
1965-01-01	34.495
1966-01-01	34.928
1967-01-01	35.361
1968-01-01	35.796
1969-01-01	36.234
1970-01-01	36.678
1971-01-01	37.128
1972-01-01	37.587
1973-01-01	38.056
1974-01-01	38.540
1975-01-01	39.039
1976-01-01	39.556
1977-01-01	40.092
1978-01-01	40.650
1979-01-01	41.234
1980-01-01	41.853
1981-01-01	42.513
1982-01-01	43.217
1983-01-01	43.963
1984-01-01	44.747
1985-01-01	45.566
1986-01-01	46.417
1987-01-01	47.288
1988-01-01	48.164
1989-01-01	49.028
1990-01-01	49.856
1991-01-01	50.627
1992-01-01	51.331
1993-01-01	51.968
1994-01-01	52.539
1995-01-01	53.055
1996-01-01	53.533
1997-01-01	53.997
1998-01-01	54.468
1999-01-01	54.959
2000-01-01	55.482
2001-01-01	56.044
2002-01-01	56.637
2003-01-01	57.250
2004-01-01	57.875
2005-01-01	58.500
2006-01-01	59.110
2007-01-01	59.694
2008-01-01	60.243
2009-01-01	60.754
2010-01-01	61.226
2011-01-01	61.666
2012-01-01	62.086
2013-01-01	62.494
2014-01-01	62.895
2015-01-01	63.288
2016-01-01	63.673