Year	Number of Years
1960-01-01	67.9029024390244
1961-01-01	68.3608048780488
1962-01-01	68.7410243902439
1963-01-01	69.0535609756098
1964-01-01	69.3099268292683
1965-01-01	69.5176341463415
1966-01-01	69.6811951219512
1967-01-01	69.8021219512195
1968-01-01	69.8829268292683
1969-01-01	69.9280975609756
1970-01-01	69.9370975609756
1971-01-01	69.9053414634146
1972-01-01	69.8328292682927
1973-01-01	69.7245853658537
1974-01-01	69.5902195121951
1975-01-01	69.4413170731707
1976-01-01	69.2900243902439
1977-01-01	69.1469512195122
1978-01-01	69.0262682926829
1979-01-01	68.9385853658537
1980-01-01	68.9056341463415
1981-01-01	68.9780487804878
1982-01-01	69.1268292682927
1983-01-01	69.3756097560976
1984-01-01	69.2780487804878
1985-01-01	69.3804878048781
1986-01-01	70.0853658536585
1987-01-01	70.6439024390244
1988-01-01	70.6975609756098
1989-01-01	70.0390243902439
1990-01-01	69.4756097560976
1991-01-01	69.3731707317073
1992-01-01	68.8634146341464
1993-01-01	67.9097560975610
1994-01-01	66.5000000000000
1995-01-01	67.5439024390244
1996-01-01	69.6121951219512
1997-01-01	69.8097560975610
1998-01-01	69.3585365853659
1999-01-01	70.0634146341463
2000-01-01	70.4170731707317
2001-01-01	70.2585365853659
2002-01-01	70.9048780487805
2003-01-01	71.3170731707317
2004-01-01	71.9097560975610
2005-01-01	72.5682926829268
2006-01-01	72.6914634146341
2007-01-01	72.8146341463415
2008-01-01	73.7707317073171
2009-01-01	74.8243902439024
2010-01-01	75.4292682926829
2011-01-01	76.2292682926829
2012-01-01	76.3268292682927
2013-01-01	77.1414634146341
2014-01-01	77.0341463414634
2015-01-01	77.5902439024390
2016-01-01	77.7365853658537