Year	Number of Years
1960-01-01	56.152
1961-01-01	56.572
1962-01-01	56.995
1963-01-01	57.419
1964-01-01	57.843
1965-01-01	58.261
1966-01-01	58.667
1967-01-01	59.059
1968-01-01	59.432
1969-01-01	59.784
1970-01-01	60.114
1971-01-01	60.422
1972-01-01	60.711
1973-01-01	60.986
1974-01-01	61.247
1975-01-01	61.499
1976-01-01	61.743
1977-01-01	61.982
1978-01-01	62.216
1979-01-01	62.445
1980-01-01	62.679
1981-01-01	62.926
1982-01-01	63.184
1983-01-01	63.442
1984-01-01	63.684
1985-01-01	63.869
1986-01-01	63.946
1987-01-01	63.896
1988-01-01	63.724
1989-01-01	63.455
1990-01-01	63.149
1991-01-01	62.880
1992-01-01	62.719
1993-01-01	62.710
1994-01-01	62.869
1995-01-01	63.185
1996-01-01	63.618
1997-01-01	64.105
1998-01-01	64.591
1999-01-01	65.053
2000-01-01	65.485
2001-01-01	65.894
2002-01-01	66.303
2003-01-01	66.727
2004-01-01	67.163
2005-01-01	67.607
2006-01-01	68.052
2007-01-01	68.487
2008-01-01	68.902
2009-01-01	69.290
2010-01-01	69.644
2011-01-01	69.958
2012-01-01	70.234
2013-01-01	70.477
2014-01-01	70.690
2015-01-01	70.879
2016-01-01	71.051