Year	Percent of Total
1960-01-01	3.69898297883640
1961-01-01	3.68732351926283
1962-01-01	3.67041068261641
1963-01-01	3.64797636978329
1964-01-01	3.62207304571595
1965-01-01	3.59299158597673
1966-01-01	3.60467258092843
1967-01-01	3.61062217800566
1968-01-01	3.60841647625785
1969-01-01	3.59412271205482
1970-01-01	3.56516791733300
1971-01-01	3.56447808077279
1972-01-01	3.54805224241387
1973-01-01	3.52135892819566
1974-01-01	3.49074972893498
1975-01-01	3.45951047644940
1976-01-01	3.47136343494307
1977-01-01	3.47832316504652
1978-01-01	3.47948689936079
1979-01-01	3.47488867321882
1980-01-01	3.46518912342792
1981-01-01	3.48112280810315
1982-01-01	3.49244485339362
1983-01-01	3.49918276243871
1984-01-01	3.49805423658035
1985-01-01	3.48810678723890
1986-01-01	3.46785166120416
1987-01-01	3.44039679291166
1988-01-01	3.41188309878940
1989-01-01	3.38788749151613
1990-01-01	3.37218277900773
1991-01-01	3.37720195941982
1992-01-01	3.38212920346616
1993-01-01	3.38471637190918
1994-01-01	3.38099156168039
1995-01-01	3.37032631592301
1996-01-01	3.36533080494512
1997-01-01	3.35418995175651
1998-01-01	3.33823787699537
1999-01-01	3.31924682003959
2000-01-01	3.29918489177610
2001-01-01	3.31325675063457
2002-01-01	3.31830387835366
2003-01-01	3.31693123957041
2004-01-01	3.31291421381745
2005-01-01	3.30711210926505
2006-01-01	3.33438080996860
2007-01-01	3.35835839445362
2008-01-01	3.37826835202659
2009-01-01	3.39202822595740
2010-01-01	3.39752527413870
2011-01-01	3.41904143353037
2012-01-01	3.43464076249573
2013-01-01	3.44741249805743
2014-01-01	3.46158907326554
2015-01-01	3.47981353592014
2016-01-01	3.51343078815976
2017-01-01	3.55241980997666