Year	Percent of Total
1960-01-01	65.3143849387680
1961-01-01	65.1735975869347
1962-01-01	65.2134904043712
1963-01-01	65.2062702606688
1964-01-01	65.0751935872307
1965-01-01	64.8610809165616
1966-01-01	64.8343328142342
1967-01-01	64.9011696205118
1968-01-01	64.8568973939996
1969-01-01	64.6617544093622
1970-01-01	64.4174360751504
1971-01-01	64.3967552465833
1972-01-01	64.5218179170644
1973-01-01	64.7528562838244
1974-01-01	65.0626183542591
1975-01-01	65.4305264406914
1976-01-01	65.5419142330302
1977-01-01	65.7289103103402
1978-01-01	65.9886961299945
1979-01-01	66.3252200607712
1980-01-01	66.7129441861916
1981-01-01	67.0928276257743
1982-01-01	67.5378330345671
1983-01-01	67.9755405776328
1984-01-01	68.3570776048863
1985-01-01	68.6633086213081
1986-01-01	68.8330991643866
1987-01-01	68.9882676497264
1988-01-01	69.0969483381215
1989-01-01	69.1815380204974
1990-01-01	69.2786715101194
1991-01-01	69.0876469258590
1992-01-01	68.9578090511606
1993-01-01	68.8416807287546
1994-01-01	68.7175696033030
1995-01-01	68.5885064493287
1996-01-01	68.5187358885306
1997-01-01	68.4548605153897
1998-01-01	68.4191148897873
1999-01-01	68.4251152775803
2000-01-01	68.4982349974786
2001-01-01	68.5145500791092
2002-01-01	68.5787370527697
2003-01-01	68.6782251805470
2004-01-01	68.7863158581968
2005-01-01	68.8639869340350
2006-01-01	68.7602550656002
2007-01-01	68.7265594551251
2008-01-01	68.7563856048635
2009-01-01	68.8253059525986
2010-01-01	68.8772472913442
2011-01-01	68.7595406767728
2012-01-01	68.6163685717473
2013-01-01	68.4393883339500
2014-01-01	68.2350631101620
2015-01-01	68.0040059111616
2016-01-01	67.7350933809810
2017-01-01	67.4449834859722