Year	Number of Years
1960-01-01	69.2744836840140
1961-01-01	69.6452667548157
1962-01-01	69.6038869024486
1963-01-01	69.7735332814793
1964-01-01	70.2334968620701
1965-01-01	70.3197947641960
1966-01-01	70.5967025836067
1967-01-01	70.7368900533402
1968-01-01	70.7871373880975
1969-01-01	70.7939165716523
1970-01-01	71.1583122930886
1971-01-01	71.2662748128238
1972-01-01	71.6058064755353
1973-01-01	71.7010345844960
1974-01-01	72.0268567829313
1975-01-01	72.1702768358900
1976-01-01	72.4357780430856
1977-01-01	72.7910814634574
1978-01-01	73.0122015847906
1979-01-01	73.3353892092198
1980-01-01	73.5296239919765
1981-01-01	73.8123426541960
1982-01-01	74.1552106037526
1983-01-01	74.2297241829691
1984-01-01	74.5878752489138
1985-01-01	74.7575598993759
1986-01-01	75.0569204700292
1987-01-01	75.3480820867599
1988-01-01	75.5356923844060
1989-01-01	75.7615255159746
1990-01-01	75.9114532653494
1991-01-01	76.0250664980680
1992-01-01	76.3800851083396
1993-01-01	76.4867305900405
1994-01-01	76.7950188371911
1995-01-01	76.9556835588635
1996-01-01	77.2182105146185
1997-01-01	77.5813573399368
1998-01-01	77.7969376438583
1999-01-01	78.0209973756490
2000-01-01	78.2748926912842
2001-01-01	78.5971155115040
2002-01-01	78.6844678776239
2003-01-01	78.7071825494894
2004-01-01	79.2787016221772
2005-01-01	79.4262861302399
2006-01-01	79.8561324119991
2007-01-01	80.0998851001265
2008-01-01	80.3029158374912
2009-01-01	80.5051815800699
2010-01-01	80.7467810041428
2011-01-01	81.2328031748937
2012-01-01	81.2270979386238
2013-01-01	81.5129528903896
2014-01-01	81.9332888456329
2015-01-01	81.5596100692018
2016-01-01	81.5599298047669