Year	Number of Years
1960-01-01	59.041
1961-01-01	59.722
1962-01-01	60.391
1963-01-01	61.024
1964-01-01	61.585
1965-01-01	61.968
1966-01-01	62.042
1967-01-01	61.773
1968-01-01	61.192
1969-01-01	60.391
1970-01-01	59.571
1971-01-01	58.989
1972-01-01	58.835
1973-01-01	59.214
1974-01-01	60.123
1975-01-01	61.458
1976-01-01	63.021
1977-01-01	64.559
1978-01-01	65.871
1979-01-01	66.877
1980-01-01	67.553
1981-01-01	67.953
1982-01-01	68.214
1983-01-01	68.450
1984-01-01	68.699
1985-01-01	68.982
1986-01-01	69.300
1987-01-01	69.626
1988-01-01	69.940
1989-01-01	70.242
1990-01-01	70.536
1991-01-01	70.826
1992-01-01	71.113
1993-01-01	71.399
1994-01-01	71.685
1995-01-01	71.968
1996-01-01	72.248
1997-01-01	72.519
1998-01-01	72.781
1999-01-01	73.030
2000-01-01	73.265
2001-01-01	73.487
2002-01-01	73.695
2003-01-01	73.893
2004-01-01	74.082
2005-01-01	74.263
2006-01-01	74.438
2007-01-01	74.609
2008-01-01	74.777
2009-01-01	74.946
2010-01-01	75.117
2011-01-01	75.294
2012-01-01	75.476
2013-01-01	75.663
2014-01-01	75.855
2015-01-01	76.052
2016-01-01	76.253