Year	Number of Years
1960-01-01	67.7080975609756
1961-01-01	68.2126585365854
1962-01-01	68.6358292682927
1963-01-01	68.9920731707317
1964-01-01	69.2899268292683
1965-01-01	69.5374146341464
1966-01-01	69.7346097560976
1967-01-01	69.8816585365854
1968-01-01	69.9826341463415
1969-01-01	70.0451463414634
1970-01-01	70.0792439024390
1971-01-01	70.0930000000000
1972-01-01	70.0924146341464
1973-01-01	70.0824390243902
1974-01-01	70.0680731707317
1975-01-01	70.0482682926829
1976-01-01	70.0159024390244
1977-01-01	69.9674146341464
1978-01-01	69.9063170731707
1979-01-01	69.8416341463415
1980-01-01	69.8020243902439
1981-01-01	69.8191707317073
1982-01-01	69.9082195121951
1983-01-01	70.0646585365854
1984-01-01	70.2719268292683
1985-01-01	70.9926829268293
1986-01-01	71.5495121951220
1987-01-01	70.9902439024390
1988-01-01	71.3414634146341
1989-01-01	71.4829268292683
1990-01-01	70.8365853658537
1991-01-01	70.3780487804878
1992-01-01	70.0219512195122
1993-01-01	68.9707317073171
1994-01-01	68.7682926829268
1995-01-01	68.4609756097561
1996-01-01	68.5121951219512
1997-01-01	68.4609756097561
1998-01-01	68.4073170731707
1999-01-01	67.9073170731707
2000-01-01	68.9121951219512
2001-01-01	68.5073170731707
2002-01-01	68.0560975609756
2003-01-01	68.5536585365854
2004-01-01	68.9560975609756
2005-01-01	68.8512195121951
2006-01-01	69.4048780487805
2007-01-01	70.2073170731707
2008-01-01	70.4560975609756
2009-01-01	70.4073170731707
2010-01-01	70.4048780487805
2011-01-01	70.5536585365854
2012-01-01	71.9658536585366
2013-01-01	72.4707317073171
2014-01-01	72.9707317073171
2015-01-01	73.6243902439025
2016-01-01	73.8268292682927