Year	Number of Years
1960-01-01	69.2475609756098
1961-01-01	70.1956097560976
1962-01-01	69.4919512195122
1963-01-01	70.3092682926829
1964-01-01	71.1212195121951
1965-01-01	71.2939024390244
1966-01-01	71.2234146341464
1967-01-01	70.4139024390244
1968-01-01	71.2251219512195
1969-01-01	70.4300000000000
1970-01-01	71.2563414634146
1971-01-01	70.8736585365854
1972-01-01	70.8995121951220
1973-01-01	71.3421951219512
1974-01-01	71.2080487804878
1975-01-01	71.0497560975610
1976-01-01	71.3948780487805
1977-01-01	70.8160975609756
1978-01-01	71.1846341463415
1979-01-01	71.3082926829268
1980-01-01	71.1575609756098
1981-01-01	71.5719512195122
1982-01-01	71.1860975609756
1983-01-01	71.3863414634146
1984-01-01	71.4997560975610
1985-01-01	71.2280487804878
1986-01-01	71.7307317073171
1987-01-01	71.5268292682927
1988-01-01	71.6043902439024
1989-01-01	71.7224390243903
1990-01-01	71.6414634146342
1991-01-01	71.5609756097561
1992-01-01	71.4943902439024
1993-01-01	71.3468292682927
1994-01-01	71.2087804878049
1995-01-01	71.0534146341464
1996-01-01	70.8973170731707
1997-01-01	70.3512195121951
1998-01-01	71.0609756097561
1999-01-01	71.4121951219512
2000-01-01	71.6634146341463
2001-01-01	71.7682926829268
2002-01-01	71.8658536585366
2003-01-01	72.0658536585366
2004-01-01	72.5634146341463
2005-01-01	72.5609756097561
2006-01-01	72.6121951219512
2007-01-01	72.6634146341463
2008-01-01	72.9634146341463
2009-01-01	73.4121951219512
2010-01-01	73.5121951219512
2011-01-01	74.1634146341463
2012-01-01	74.3146341463415
2013-01-01	74.8609756097561
2014-01-01	74.4658536585366
2015-01-01	74.6146341463415
2016-01-01	74.6146341463415