Year	Percent of Total
1960-01-01	38.2438936141344
1961-01-01	38.6382139473080
1962-01-01	38.9609555323863
1963-01-01	39.2278669637266
1964-01-01	39.4410571871853
1965-01-01	39.6029798045042
1966-01-01	39.9617323821889
1967-01-01	40.2259858734100
1968-01-01	40.4137308698466
1969-01-01	40.5389405318543
1970-01-01	40.6106165606447
1971-01-01	40.9692062310482
1972-01-01	41.2361200789131
1973-01-01	41.4320535345958
1974-01-01	41.5801704967955
1975-01-01	41.6971188258784
1976-01-01	41.8939539033313
1977-01-01	42.0212304728312
1978-01-01	42.1008403749984
1979-01-01	42.1547615023157
1980-01-01	42.1975234020566
1981-01-01	42.2947958430150
1982-01-01	42.3544470003026
1983-01-01	42.3845078585796
1984-01-01	42.3798709409880
1985-01-01	42.3331354261887
1986-01-01	42.6365841522116
1987-01-01	42.8660764709042
1988-01-01	43.0303344944464
1989-01-01	43.1433427044128
1990-01-01	43.2140500309547
1991-01-01	43.2104302228072
1992-01-01	43.1319523471586
1993-01-01	42.9958047567884
1994-01-01	42.8162268527728
1995-01-01	42.6016779573409
1996-01-01	42.5989305030734
1997-01-01	42.5576200441872
1998-01-01	42.4759095843230
1999-01-01	42.3502138442239
2000-01-01	42.1825540761004
2001-01-01	42.2841900598690
2002-01-01	42.3150251355559
2003-01-01	42.2929603570366
2004-01-01	42.2392304285338
2005-01-01	42.1631285565819
2006-01-01	42.3162400119188
2007-01-01	42.4277562093643
2008-01-01	42.4952581888007
2009-01-01	42.5105864135161
2010-01-01	42.4657161643466
2011-01-01	42.8133712140760
2012-01-01	43.1242895981130
2013-01-01	43.3813896316005
2014-01-01	43.5779440633283
2015-01-01	43.7183519940169
2016-01-01	43.5016729345032
2017-01-01	43.1957811413412