Year	Number of Years
1960-01-01	68.1639024390244
1961-01-01	68.5486341463415
1962-01-01	68.8922682926829
1963-01-01	69.1857073170732
1964-01-01	69.4294390243902
1965-01-01	69.6380000000000
1966-01-01	69.8374634146341
1967-01-01	70.0524634146342
1968-01-01	70.3025609756098
1969-01-01	70.5892926829268
1970-01-01	70.9036341463415
1971-01-01	71.2265609756098
1972-01-01	71.5350000000000
1973-01-01	71.8148536585366
1974-01-01	72.0646341463415
1975-01-01	72.2937073170732
1976-01-01	72.5195609756098
1977-01-01	72.7616585365854
1978-01-01	73.0310731707317
1979-01-01	73.3293658536585
1980-01-01	73.6471463414634
1981-01-01	73.9694878048781
1982-01-01	74.2790000000000
1983-01-01	74.5658536585366
1984-01-01	74.8291219512195
1985-01-01	75.0785121951220
1986-01-01	75.3297073170732
1987-01-01	75.5981463414634
1988-01-01	75.8912439024390
1989-01-01	76.6878048780488
1990-01-01	76.9390243902439
1991-01-01	77.1365853658537
1992-01-01	77.3829268292683
1993-01-01	77.3902439024390
1994-01-01	77.6390243902439
1995-01-01	77.5853658536585
1996-01-01	77.6853658536585
1997-01-01	78.1365853658537
1998-01-01	77.8390243902439
1999-01-01	77.9878048780488
2000-01-01	77.8878048780488
2001-01-01	78.3878048780488
2002-01-01	78.6414634146341
2003-01-01	78.8414634146341
2004-01-01	79.0390243902439
2005-01-01	79.2390243902439
2006-01-01	79.4390243902439
2007-01-01	79.4390243902439
2008-01-01	79.9390243902439
2009-01-01	80.1878048780488
2010-01-01	80.3878048780488
2011-01-01	80.7317073170732
2012-01-01	80.6341463414634
2013-01-01	81.2853658536585
2014-01-01	81.3853658536585
2015-01-01	81.0365853658537
2016-01-01	81.0365853658537