Year	Number of Years
1960-01-01	44.038
1961-01-01	44.469
1962-01-01	44.892
1963-01-01	45.309
1964-01-01	45.727
1965-01-01	46.166
1966-01-01	46.654
1967-01-01	47.203
1968-01-01	47.814
1969-01-01	48.476
1970-01-01	49.160
1971-01-01	49.827
1972-01-01	50.442
1973-01-01	50.982
1974-01-01	51.442
1975-01-01	51.832
1976-01-01	52.177
1977-01-01	52.513
1978-01-01	52.865
1979-01-01	53.241
1980-01-01	53.639
1981-01-01	54.049
1982-01-01	54.451
1983-01-01	54.828
1984-01-01	55.174
1985-01-01	55.488
1986-01-01	55.772
1987-01-01	56.032
1988-01-01	56.271
1989-01-01	56.488
1990-01-01	56.678
1991-01-01	56.831
1992-01-01	56.943
1993-01-01	57.017
1994-01-01	57.056
1995-01-01	57.065
1996-01-01	57.050
1997-01-01	57.022
1998-01-01	56.998
1999-01-01	56.992
2000-01-01	57.021
2001-01-01	57.100
2002-01-01	57.233
2003-01-01	57.424
2004-01-01	57.677
2005-01-01	57.999
2006-01-01	58.393
2007-01-01	58.848
2008-01-01	59.345
2009-01-01	59.865
2010-01-01	60.383
2011-01-01	60.870
2012-01-01	61.310
2013-01-01	61.691
2014-01-01	62.006
2015-01-01	62.260
2016-01-01	62.465