Year	Number of Years
1960-01-01	52.265
1961-01-01	53.312
1962-01-01	54.349
1963-01-01	55.375
1964-01-01	56.385
1965-01-01	57.374
1966-01-01	58.330
1967-01-01	59.248
1968-01-01	60.120
1969-01-01	60.945
1970-01-01	61.721
1971-01-01	62.451
1972-01-01	63.143
1973-01-01	63.802
1974-01-01	64.433
1975-01-01	65.037
1976-01-01	65.617
1977-01-01	66.171
1978-01-01	66.701
1979-01-01	67.209
1980-01-01	67.696
1981-01-01	68.163
1982-01-01	68.611
1983-01-01	69.040
1984-01-01	69.452
1985-01-01	69.845
1986-01-01	70.219
1987-01-01	70.575
1988-01-01	70.913
1989-01-01	71.234
1990-01-01	71.541
1991-01-01	71.837
1992-01-01	72.122
1993-01-01	72.401
1994-01-01	72.674
1995-01-01	72.943
1996-01-01	73.210
1997-01-01	73.473
1998-01-01	73.732
1999-01-01	73.987
2000-01-01	74.239
2001-01-01	74.487
2002-01-01	74.730
2003-01-01	74.968
2004-01-01	75.200
2005-01-01	75.422
2006-01-01	75.632
2007-01-01	75.828
2008-01-01	76.012
2009-01-01	76.183
2010-01-01	76.344
2011-01-01	76.498
2012-01-01	76.648
2013-01-01	76.798
2014-01-01	76.948
2015-01-01	77.101
2016-01-01	77.256