Year	Number of Years
1960-01-01	34.526
1961-01-01	34.889
1962-01-01	35.290
1963-01-01	35.734
1964-01-01	36.220
1965-01-01	36.745
1966-01-01	37.303
1967-01-01	37.882
1968-01-01	38.469
1969-01-01	39.057
1970-01-01	39.635
1971-01-01	40.194
1972-01-01	40.735
1973-01-01	41.263
1974-01-01	41.784
1975-01-01	42.311
1976-01-01	42.861
1977-01-01	43.447
1978-01-01	44.077
1979-01-01	44.751
1980-01-01	45.464
1981-01-01	46.204
1982-01-01	46.954
1983-01-01	47.702
1984-01-01	48.442
1985-01-01	49.173
1986-01-01	49.901
1987-01-01	50.632
1988-01-01	51.372
1989-01-01	52.122
1990-01-01	52.879
1991-01-01	53.637
1992-01-01	54.393
1993-01-01	55.146
1994-01-01	55.898
1995-01-01	56.657
1996-01-01	57.432
1997-01-01	58.231
1998-01-01	59.055
1999-01-01	59.899
2000-01-01	60.758
2001-01-01	61.625
2002-01-01	62.484
2003-01-01	63.322
2004-01-01	64.126
2005-01-01	64.882
2006-01-01	65.578
2007-01-01	66.214
2008-01-01	66.792
2009-01-01	67.315
2010-01-01	67.790
2011-01-01	68.227
2012-01-01	68.639
2013-01-01	69.038
2014-01-01	69.430
2015-01-01	69.817
2016-01-01	70.197