Year	Percent of Total
1960-01-01	8.19198128966276
1961-01-01	8.29071857385251
1962-01-01	8.38616945410849
1963-01-01	8.48427970918386
1964-01-01	8.59338335496706
1965-01-01	8.72042251985598
1966-01-01	8.89412740764453
1967-01-01	9.07840375412899
1968-01-01	9.26675803750542
1969-01-01	9.44890125879561
1970-01-01	9.61886536766211
1971-01-01	9.77394980903952
1972-01-01	9.90400546919290
1973-01-01	10.01981854005610
1974-01-01	10.13368032070640
1975-01-01	10.25213203819720
1976-01-01	10.42497614995700
1977-01-01	10.60394392496980
1978-01-01	10.78064222817870
1979-01-01	10.94147915996450
1980-01-01	11.08189728785210
1981-01-01	11.22777070011500
1982-01-01	11.35812274856370
1983-01-01	11.49055406024310
1984-01-01	11.64925822190380
1985-01-01	11.84926291364970
1986-01-01	12.11803745739590
1987-01-01	12.40952855494320
1988-01-01	12.72374753155880
1989-01-01	13.05752371006490
1990-01-01	13.40685474229930
1991-01-01	13.73459769764890
1992-01-01	14.06703560027350
1993-01-01	14.40788513529790
1994-01-01	14.76187767389470
1995-01-01	15.13185922121100
1996-01-01	15.46326801222640
1997-01-01	15.81259487545460
1998-01-01	16.15621780274420
1999-01-01	16.45934531915770
2000-01-01	16.70288057726600
2001-01-01	16.75958334371170
2002-01-01	16.75661751956390
2003-01-01	16.72343118390120
2004-01-01	16.69971729807490
2005-01-01	16.70836111701950
2006-01-01	16.76046692971700
2007-01-01	16.83379940960300
2008-01-01	16.93006401218350
2009-01-01	17.05137000390220
2010-01-01	17.20326711852860
2011-01-01	17.49391770959420
2012-01-01	17.81650985189020
2013-01-01	18.16437148216310
2014-01-01	18.52117931653890
2015-01-01	18.87752581681700
2016-01-01	19.16702612451620
2017-01-01	19.43639515289200