Year	Number of Years
1960-01-01	56.282
1961-01-01	56.708
1962-01-01	57.093
1963-01-01	57.465
1964-01-01	57.845
1965-01-01	58.242
1966-01-01	58.654
1967-01-01	59.061
1968-01-01	59.452
1969-01-01	59.828
1970-01-01	60.184
1971-01-01	60.518
1972-01-01	60.836
1973-01-01	61.147
1974-01-01	61.465
1975-01-01	61.816
1976-01-01	62.230
1977-01-01	62.717
1978-01-01	63.278
1979-01-01	63.902
1980-01-01	64.562
1981-01-01	65.220
1982-01-01	65.840
1983-01-01	66.394
1984-01-01	66.871
1985-01-01	67.267
1986-01-01	67.594
1987-01-01	67.879
1988-01-01	68.149
1989-01-01	68.418
1990-01-01	68.700
1991-01-01	69.005
1992-01-01	69.332
1993-01-01	69.680
1994-01-01	70.047
1995-01-01	70.430
1996-01-01	70.821
1997-01-01	71.209
1998-01-01	71.587
1999-01-01	71.955
2000-01-01	72.313
2001-01-01	72.669
2002-01-01	73.029
2003-01-01	73.396
2004-01-01	73.766
2005-01-01	74.132
2006-01-01	74.486
2007-01-01	74.818
2008-01-01	75.123
2009-01-01	75.397
2010-01-01	75.643
2011-01-01	75.862
2012-01-01	76.065
2013-01-01	76.257
2014-01-01	76.444
2015-01-01	76.628
2016-01-01	76.813