Year	Number of Years
1960-01-01	37.805
1961-01-01	38.031
1962-01-01	38.249
1963-01-01	38.458
1964-01-01	38.664
1965-01-01	38.881
1966-01-01	39.127
1967-01-01	39.415
1968-01-01	39.750
1969-01-01	40.134
1970-01-01	40.558
1971-01-01	41.011
1972-01-01	41.475
1973-01-01	41.932
1974-01-01	42.376
1975-01-01	42.802
1976-01-01	43.215
1977-01-01	43.621
1978-01-01	44.020
1979-01-01	44.408
1980-01-01	44.776
1981-01-01	45.112
1982-01-01	45.411
1983-01-01	45.668
1984-01-01	45.882
1985-01-01	46.055
1986-01-01	46.196
1987-01-01	46.313
1988-01-01	46.414
1989-01-01	46.503
1990-01-01	46.576
1991-01-01	46.627
1992-01-01	46.650
1993-01-01	46.647
1994-01-01	46.627
1995-01-01	46.585
1996-01-01	46.516
1997-01-01	46.434
1998-01-01	46.369
1999-01-01	46.355
2000-01-01	46.450
2001-01-01	46.710
2002-01-01	47.169
2003-01-01	47.843
2004-01-01	48.735
2005-01-01	49.846
2006-01-01	51.163
2007-01-01	52.630
2008-01-01	54.177
2009-01-01	55.745
2010-01-01	57.263
2011-01-01	58.667
2012-01-01	59.927
2013-01-01	61.020
2014-01-01	61.932
2015-01-01	62.661
2016-01-01	63.223