Year	Number of Years
1960-01-01	62.881
1961-01-01	63.220
1962-01-01	63.551
1963-01-01	63.873
1964-01-01	64.189
1965-01-01	64.498
1966-01-01	64.800
1967-01-01	65.095
1968-01-01	65.383
1969-01-01	65.665
1970-01-01	65.943
1971-01-01	66.218
1972-01-01	66.490
1973-01-01	66.759
1974-01-01	67.027
1975-01-01	67.291
1976-01-01	67.550
1977-01-01	67.803
1978-01-01	68.050
1979-01-01	68.290
1980-01-01	68.524
1981-01-01	68.755
1982-01-01	68.984
1983-01-01	69.212
1984-01-01	69.438
1985-01-01	69.663
1986-01-01	69.886
1987-01-01	70.104
1988-01-01	70.316
1989-01-01	70.518
1990-01-01	70.705
1991-01-01	70.869
1992-01-01	71.010
1993-01-01	71.131
1994-01-01	71.239
1995-01-01	71.351
1996-01-01	71.482
1997-01-01	71.646
1998-01-01	71.850
1999-01-01	72.093
2000-01-01	72.370
2001-01-01	72.668
2002-01-01	72.971
2003-01-01	73.264
2004-01-01	73.538
2005-01-01	73.787
2006-01-01	74.012
2007-01-01	74.218
2008-01-01	74.410
2009-01-01	74.591
2010-01-01	74.761
2011-01-01	74.923
2012-01-01	75.079
2013-01-01	75.230
2014-01-01	75.379
2015-01-01	75.527
2016-01-01	75.675