Year	Number of Years
1960-01-01	67.3597358712176
1961-01-01	67.7549287555868
1962-01-01	67.7576559352779
1963-01-01	67.9803918479882
1964-01-01	68.3857641041379
1965-01-01	68.5106633902504
1966-01-01	68.7843262893773
1967-01-01	69.0198778925859
1968-01-01	68.9854993491979
1969-01-01	69.1845177837151
1970-01-01	69.5144852623405
1971-01-01	69.8002497985408
1972-01-01	70.0923523272240
1973-01-01	70.2774018088530
1974-01-01	70.6925780738262
1975-01-01	71.0406542978936
1976-01-01	71.3170166311352
1977-01-01	71.6821231115374
1978-01-01	71.8595792006104
1979-01-01	72.2017857751679
1980-01-01	72.2595716348733
1981-01-01	72.6286300245606
1982-01-01	72.9719447896142
1983-01-01	73.1050575807749
1984-01-01	73.3956710328344
1985-01-01	73.5371377377180
1986-01-01	73.8018105655187
1987-01-01	74.0880315375706
1988-01-01	74.2338136979466
1989-01-01	74.5005579634814
1990-01-01	74.6842372871545
1991-01-01	74.8762072477604
1992-01-01	75.1523725343729
1993-01-01	75.2699125689478
1994-01-01	75.5734913435129
1995-01-01	75.6825463651970
1996-01-01	76.0616020751106
1997-01-01	76.4034573122457
1998-01-01	76.6116306436247
1999-01-01	76.7826025324343
2000-01-01	77.0659518525534
2001-01-01	77.3695487465380
2002-01-01	77.5236791634845
2003-01-01	77.6734691491778
2004-01-01	78.0835869806107
2005-01-01	78.2045625259751
2006-01-01	78.5008900598936
2007-01-01	78.7383686182288
2008-01-01	78.8965305375477
2009-01-01	79.1651373087896
2010-01-01	79.3458206077777
2011-01-01	79.5886785628848
2012-01-01	79.7103622897796
2013-01-01	79.8868716366666
2014-01-01	80.1510449789881
2015-01-01	80.0540775191875
2016-01-01	80.1110227025325