Year	Number of Years
1960-01-01	69.7868292682927
1961-01-01	70.0324390243903
1962-01-01	69.4304878048780
1963-01-01	69.8290243902439
1964-01-01	71.0280487804878
1965-01-01	70.7265853658537
1966-01-01	70.7073170731707
1967-01-01	70.3939024390244
1968-01-01	70.0429268292683
1969-01-01	69.7968292682927
1970-01-01	69.8353658536586
1971-01-01	70.1646341463415
1972-01-01	69.8787804878049
1973-01-01	69.8134146341464
1974-01-01	69.7409756097561
1975-01-01	68.9253658536585
1976-01-01	69.0478048780488
1977-01-01	69.1046341463415
1978-01-01	68.9878048780488
1979-01-01	68.4956097560976
1980-01-01	68.8085365853659
1981-01-01	68.7863414634146
1982-01-01	69.3282926829268
1983-01-01	69.1190243902439
1984-01-01	69.1629268292683
1985-01-01	69.2914634146342
1986-01-01	70.6224390243903
1987-01-01	70.6929268292683
1988-01-01	70.6153658536585
1989-01-01	70.1553658536586
1990-01-01	69.2731707317073
1991-01-01	69.0324390243903
1992-01-01	68.3960975609756
1993-01-01	66.7226829268293
1994-01-01	65.6643902439025
1995-01-01	66.3912195121951
1996-01-01	68.7765853658537
1997-01-01	69.3492682926829
1998-01-01	69.0121951219512
1999-01-01	69.7429268292683
2000-01-01	70.3146341463415
2001-01-01	70.7609756097561
2002-01-01	70.9609756097561
2003-01-01	71.2658536585366
2004-01-01	72.0268292682927
2005-01-01	71.3560975609756
2006-01-01	70.8658536585366
2007-01-01	71.0195121951220
2008-01-01	72.4195121951220
2009-01-01	73.0804878048781
2010-01-01	73.4829268292683
2011-01-01	73.5756097560976
2012-01-01	73.7780487804878
2013-01-01	73.9829268292683
2014-01-01	74.1243902439024
2015-01-01	74.4804878048781
2016-01-01	74.5292682926829