Year	Number of Years
1960-01-01	46.138
1961-01-01	46.596
1962-01-01	47.054
1963-01-01	47.507
1964-01-01	47.956
1965-01-01	48.392
1966-01-01	48.809
1967-01-01	49.208
1968-01-01	49.595
1969-01-01	49.980
1970-01-01	50.369
1971-01-01	50.770
1972-01-01	51.198
1973-01-01	51.673
1974-01-01	52.215
1975-01-01	52.863
1976-01-01	53.658
1977-01-01	54.606
1978-01-01	55.696
1979-01-01	56.906
1980-01-01	58.196
1981-01-01	59.521
1982-01-01	60.823
1983-01-01	62.047
1984-01-01	63.156
1985-01-01	64.113
1986-01-01	64.896
1987-01-01	65.525
1988-01-01	66.025
1989-01-01	66.416
1990-01-01	66.725
1991-01-01	66.983
1992-01-01	67.226
1993-01-01	67.482
1994-01-01	67.774
1995-01-01	68.115
1996-01-01	68.504
1997-01-01	68.926
1998-01-01	69.367
1999-01-01	69.822
2000-01-01	70.292
2001-01-01	70.778
2002-01-01	71.276
2003-01-01	71.780
2004-01-01	72.281
2005-01-01	72.767
2006-01-01	73.225
2007-01-01	73.648
2008-01-01	74.032
2009-01-01	74.374
2010-01-01	74.676
2011-01-01	74.944
2012-01-01	75.187
2013-01-01	75.418
2014-01-01	75.641
2015-01-01	75.860
2016-01-01	76.078