Year	Number of Years
1960-01-01	51.4483042160472
1961-01-01	51.9004871043380
1962-01-01	52.3416140638460
1963-01-01	52.7449326496251
1964-01-01	53.1484743743730
1965-01-01	53.5227122221315
1966-01-01	53.8544370658132
1967-01-01	54.1899386770523
1968-01-01	54.5196934319639
1969-01-01	54.8460389834915
1970-01-01	55.1850914352580
1971-01-01	55.5137173365253
1972-01-01	55.8510039190849
1973-01-01	56.1570598017170
1974-01-01	56.4596576812322
1975-01-01	56.7980191303731
1976-01-01	57.1799090290030
1977-01-01	57.5780001140569
1978-01-01	58.0356486065551
1979-01-01	58.5137032848941
1980-01-01	59.0430518806806
1981-01-01	59.5089140479011
1982-01-01	59.9665083546567
1983-01-01	60.3942800981512
1984-01-01	60.7567306144429
1985-01-01	61.1080837584975
1986-01-01	61.4940828269771
1987-01-01	61.8278732247847
1988-01-01	62.0970157721053
1989-01-01	62.2802689646672
1990-01-01	62.4029035365036
1991-01-01	62.5223193852735
1992-01-01	62.4883391820747
1993-01-01	62.3125689436733
1994-01-01	62.0464793322153
1995-01-01	61.8882752739584
1996-01-01	61.7411715396546
1997-01-01	61.4295617332091
1998-01-01	61.0805217742880
1999-01-01	60.8550799011749
2000-01-01	60.7265064948918
2001-01-01	60.6433356946832
2002-01-01	60.7039054338289
2003-01-01	60.8951704128028
2004-01-01	61.2529545769101
2005-01-01	61.7332174399686
2006-01-01	62.2798857638404
2007-01-01	62.9200097940307
2008-01-01	63.6093742903757
2009-01-01	64.3127492193275
2010-01-01	64.9491907478681
2011-01-01	65.5260966183799
2012-01-01	66.0780866933603
2013-01-01	66.5481671616232
2014-01-01	66.9694323628376
2015-01-01	67.3639125558869
2016-01-01	67.6950312773975