Year	Percent of Total
1960-01-01	6.81132247043592
1961-01-01	6.89361959271057
1962-01-01	6.95054732443053
1963-01-01	7.00253010655559
1964-01-01	7.07662003777494
1965-01-01	7.18940919557810
1966-01-01	7.36345766043619
1967-01-01	7.57920894595154
1968-01-01	7.81790816993326
1969-01-01	8.04874050598328
1970-01-01	8.25713424437299
1971-01-01	8.47543066636116
1972-01-01	8.73836672313319
1973-01-01	9.07949756354537
1974-01-01	9.48805711972324
1975-01-01	9.90879309363747
1976-01-01	10.07217794733350
1977-01-01	10.19920895234420
1978-01-01	10.31467972099570
1979-01-01	10.42611385596610
1980-01-01	10.52642013687880
1981-01-01	10.58479532163740
1982-01-01	10.57788142971390
1983-01-01	10.52224204182020
1984-01-01	10.44346827695120
1985-01-01	10.34721245369720
1986-01-01	10.30124330051100
1987-01-01	10.24606868495520
1988-01-01	10.18655691668570
1989-01-01	10.13034864987780
1990-01-01	10.08587647000080
1991-01-01	10.18773323126970
1992-01-01	10.30879077289230
1993-01-01	10.43601214798030
1994-01-01	10.56000606026170
1995-01-01	10.67674621356510
1996-01-01	10.82341262380520
1997-01-01	10.97641836333330
1998-01-01	11.13976488150770
1999-01-01	11.32261399216130
2000-01-01	11.52690228166330
2001-01-01	11.57655577516300
2002-01-01	11.61788432211820
2003-01-01	11.65512124528940
2004-01-01	11.68841155512270
2005-01-01	11.72041794247630
2006-01-01	11.81759677718430
2007-01-01	11.92431649465870
2008-01-01	12.05759432278350
2009-01-01	12.23435199482890
2010-01-01	12.46561671716110
2011-01-01	12.72661180822590
2012-01-01	13.03052364294970
2013-01-01	13.37975073360490
2014-01-01	13.75937329075290
2015-01-01	14.16382552767780
2016-01-01	14.54967789021600
2017-01-01	14.95210329029570