Year	Number of Years
1960-01-01	37.397
1961-01-01	37.995
1962-01-01	38.626
1963-01-01	39.281
1964-01-01	39.956
1965-01-01	40.643
1966-01-01	41.339
1967-01-01	42.046
1968-01-01	42.764
1969-01-01	43.495
1970-01-01	44.241
1971-01-01	45.009
1972-01-01	45.803
1973-01-01	46.624
1974-01-01	47.474
1975-01-01	48.355
1976-01-01	49.271
1977-01-01	50.215
1978-01-01	51.180
1979-01-01	52.154
1980-01-01	53.120
1981-01-01	54.061
1982-01-01	54.964
1983-01-01	55.826
1984-01-01	56.648
1985-01-01	57.437
1986-01-01	58.208
1987-01-01	58.980
1988-01-01	59.766
1989-01-01	60.573
1990-01-01	61.399
1991-01-01	62.237
1992-01-01	63.077
1993-01-01	63.911
1994-01-01	64.739
1995-01-01	65.568
1996-01-01	66.408
1997-01-01	67.267
1998-01-01	68.144
1999-01-01	69.035
2000-01-01	69.936
2001-01-01	70.842
2002-01-01	71.737
2003-01-01	72.603
2004-01-01	73.418
2005-01-01	74.151
2006-01-01	74.771
2007-01-01	75.269
2008-01-01	75.648
2009-01-01	75.920
2010-01-01	76.112
2011-01-01	76.259
2012-01-01	76.401
2013-01-01	76.571
2014-01-01	76.783
2015-01-01	77.042
2016-01-01	77.339