Year	Number of Years
1960-01-01	54.241
1961-01-01	54.754
1962-01-01	55.270
1963-01-01	55.785
1964-01-01	56.293
1965-01-01	56.794
1966-01-01	57.289
1967-01-01	57.776
1968-01-01	58.254
1969-01-01	58.717
1970-01-01	59.154
1971-01-01	59.557
1972-01-01	59.919
1973-01-01	60.241
1974-01-01	60.527
1975-01-01	60.782
1976-01-01	61.017
1977-01-01	61.244
1978-01-01	61.476
1979-01-01	61.721
1980-01-01	61.983
1981-01-01	62.264
1982-01-01	62.559
1983-01-01	62.866
1984-01-01	63.185
1985-01-01	63.514
1986-01-01	63.852
1987-01-01	64.197
1988-01-01	64.552
1989-01-01	64.917
1990-01-01	65.300
1991-01-01	65.708
1992-01-01	66.144
1993-01-01	66.607
1994-01-01	67.095
1995-01-01	67.600
1996-01-01	68.112
1997-01-01	68.622
1998-01-01	69.120
1999-01-01	69.599
2000-01-01	70.055
2001-01-01	70.486
2002-01-01	70.896
2003-01-01	71.290
2004-01-01	71.670
2005-01-01	72.040
2006-01-01	72.405
2007-01-01	72.768
2008-01-01	73.129
2009-01-01	73.488
2010-01-01	73.838
2011-01-01	74.174
2012-01-01	74.488
2013-01-01	74.777
2014-01-01	75.042
2015-01-01	75.284
2016-01-01	75.509