Year	Number of Years
1960-01-01	43.686
1961-01-01	43.940
1962-01-01	44.195
1963-01-01	44.456
1964-01-01	44.731
1965-01-01	45.022
1966-01-01	45.330
1967-01-01	45.654
1968-01-01	45.993
1969-01-01	46.345
1970-01-01	46.718
1971-01-01	47.119
1972-01-01	47.546
1973-01-01	47.992
1974-01-01	48.447
1975-01-01	48.891
1976-01-01	49.306
1977-01-01	49.675
1978-01-01	49.987
1979-01-01	50.237
1980-01-01	50.429
1981-01-01	50.576
1982-01-01	50.692
1983-01-01	50.788
1984-01-01	50.863
1985-01-01	50.904
1986-01-01	50.888
1987-01-01	50.803
1988-01-01	50.651
1989-01-01	50.447
1990-01-01	50.206
1991-01-01	49.953
1992-01-01	49.719
1993-01-01	49.540
1994-01-01	49.444
1995-01-01	49.460
1996-01-01	49.609
1997-01-01	49.889
1998-01-01	50.297
1999-01-01	50.831
2000-01-01	51.493
2001-01-01	52.281
2002-01-01	53.173
2003-01-01	54.142
2004-01-01	55.161
2005-01-01	56.196
2006-01-01	57.218
2007-01-01	58.209
2008-01-01	59.156
2009-01-01	60.048
2010-01-01	60.893
2011-01-01	61.713
2012-01-01	62.528
2013-01-01	63.348
2014-01-01	64.163
2015-01-01	64.950
2016-01-01	65.675