Annual Number of Years
1960-01-01 54.7490796623698
1961-01-01 55.2165083867581
1962-01-01 55.6644912202910
1963-01-01 56.0739822446309
1964-01-01 56.4680388715591
1965-01-01 56.8278757862515
1966-01-01 57.1467537634355
1967-01-01 57.4580751413042
1968-01-01 57.7581883566100
1969-01-01 58.0524094420715
1970-01-01 58.3539538537079
1971-01-01 58.6490818471180
1972-01-01 58.9513226240777
1973-01-01 59.2346684447264
1974-01-01 59.5171753954714
1975-01-01 59.8235468289351
1976-01-01 60.1592947384945
1977-01-01 60.5040735890662
1978-01-01 60.8851978791818
1979-01-01 61.2747638239571
1980-01-01 61.6838461589020
1981-01-01 62.0510831344285
1982-01-01 62.4389322288054
1983-01-01 62.7280085521790
1984-01-01 62.9979555027171
1985-01-01 63.2508929280053
1986-01-01 63.5207361574137
1987-01-01 63.7961452991852
1988-01-01 63.9410486013923
1989-01-01 64.0748803475953
1990-01-01 64.1753257138541
1991-01-01 64.2722271691349
1992-01-01 64.3008293754171
1993-01-01 64.1665810740417
1994-01-01 64.0001945370889
1995-01-01 63.9144718082146
1996-01-01 63.8257643440961
1997-01-01 63.6665505336385
1998-01-01 63.3990249306703
1999-01-01 63.2679285641778
2000-01-01 63.2017216176221
2001-01-01 63.1638102532310
2002-01-01 63.2845825355604
2003-01-01 63.4158079574624
2004-01-01 63.7125820528742
2005-01-01 64.1026305683931
2006-01-01 64.5355775875897
2007-01-01 65.0410626374650
2008-01-01 65.5840544655187
2009-01-01 66.1397443703018
2010-01-01 66.6469087860998
2011-01-01 67.1100546688337
2012-01-01 67.5523017809790
2013-01-01 67.9348940975643
2014-01-01 68.2783177925297
2015-01-01 68.6005261847654
2016-01-01 68.8744875145215