Year	Percent of Total
1960-01-01	51.7323067190692
1961-01-01	51.4915081946836
1962-01-01	51.1538510663674
1963-01-01	50.8210636690020
1964-01-01	50.6446492133168
1965-01-01	50.6936003341169
1966-01-01	50.6775639407687
1967-01-01	50.8741465069516
1968-01-01	51.2190865447666
1969-01-01	51.5859148410625
1970-01-01	51.8958953789989
1971-01-01	52.1485835380314
1972-01-01	52.3108559931355
1973-01-01	52.4453811019721
1974-01-01	52.7209064315062
1975-01-01	53.2746620746330
1976-01-01	53.6748908160386
1977-01-01	54.3981127226231
1978-01-01	55.3039249429881
1979-01-01	56.0199824959623
1980-01-01	56.2229802960413
1981-01-01	56.6930287856320
1982-01-01	56.4024289324484
1983-01-01	55.6809792534732
1984-01-01	55.0560238967964
1985-01-01	54.7561266219092
1986-01-01	53.8170613908121
1987-01-01	53.5647167039387
1988-01-01	53.6028370610726
1989-01-01	53.4155231718815
1990-01-01	52.8144363604998
1991-01-01	52.4318895623290
1992-01-01	51.7047542671083
1993-01-01	50.9085774619982
1994-01-01	50.4465275914324
1995-01-01	50.4916479546082
1996-01-01	50.6807435479974
1997-01-01	51.3986958076750
1998-01-01	52.5706088057336
1999-01-01	53.9486652065075
2000-01-01	55.3291732614109
2001-01-01	56.5078190454436
2002-01-01	57.4490200779138
2003-01-01	58.1877137418109
2004-01-01	58.8524008761288
2005-01-01	59.5471538072407
2006-01-01	60.2995334368524
2007-01-01	61.0424318217862
2008-01-01	61.7702852251311
2009-01-01	62.4191992055760
2010-01-01	62.9400003075044
2011-01-01	63.2826533376311
2012-01-01	63.6440974696529
2013-01-01	63.9594221861169
2014-01-01	64.1739425399734
2015-01-01	64.2785256902872
2016-01-01	64.3503737064921
2017-01-01	64.3091979174744