Annual Percent of Total
1960-01-01 11.7592374677967
1961-01-01 11.9379069374295
1962-01-01 12.1214196169015
1963-01-01 12.3086980638167
1964-01-01 12.4956125686735
1965-01-01 12.6818547594250
1966-01-01 12.8898695698831
1967-01-01 13.0905557924948
1968-01-01 13.2877639561831
1969-01-01 13.4892670855416
1970-01-01 13.7008132673264
1971-01-01 13.9955406468520
1972-01-01 14.2877463044944
1973-01-01 14.5770436667755
1974-01-01 14.8609463604457
1975-01-01 15.1381179748553
1976-01-01 15.4118037773148
1977-01-01 15.6700859745755
1978-01-01 15.9108267388825
1979-01-01 16.1284158571991
1980-01-01 16.3212702514015
1981-01-01 16.5609532072155
1982-01-01 16.7580355186583
1983-01-01 16.9297767773509
1984-01-01 17.0978149833822
1985-01-01 17.2719203910381
1986-01-01 17.4295756380837
1987-01-01 17.5791017183593
1988-01-01 17.7066475506117
1989-01-01 17.7914769738952
1990-01-01 17.8237370940768
1991-01-01 17.8238444212538
1992-01-01 17.7803797006425
1993-01-01 17.7023396963636
1994-01-01 17.6063855541919
1995-01-01 17.5084140409804
1996-01-01 17.4642921684384
1997-01-01 17.4271238907669
1998-01-01 17.3938049665601
1999-01-01 17.3536419064363
2000-01-01 17.3036849050401
2001-01-01 17.3040663004860
2002-01-01 17.2625582718116
2003-01-01 17.2186273867996
2004-01-01 17.2246043913008
2005-01-01 17.3066074334553
2006-01-01 17.3959550866158
2007-01-01 17.5486888211957
2008-01-01 17.7485603920800
2009-01-01 17.9741230934351
2010-01-01 18.2185664835816
2011-01-01 18.4993025485607
2012-01-01 18.8066082186945
2013-01-01 19.1161079897376
2014-01-01 19.3884828083872
2015-01-01 19.5977493876468
2016-01-01 19.8338343566421
2017-01-01 19.9851049890416