Year	Percent
1968-01-01	0.985671714144749
1969-01-01	0.948761931843658
1970-01-01	0.828775209849381
1971-01-01	1.000549154052420
1972-01-01	1.038172963180580
1973-01-01	1.009063956441630
1974-01-01	1.232171193979650
1975-01-01	1.611016334202130
1976-01-01	1.569245423450930
1977-01-01	1.749555502262040
1978-01-01	1.935833119454640
1979-01-01	1.914900565026240
1980-01-01	1.913660426669630
1981-01-01	1.954085176206640
1982-01-01	2.102777368658680
1983-01-01	2.513781686691850
1984-01-01	2.600431255583130
1985-01-01	2.482211557893680
1986-01-01	2.601814623569220
1987-01-01	2.620494388068010
1988-01-01	2.407691852127110
1989-01-01	2.133777017381430
1990-01-01	2.043699022323550
1991-01-01	2.064838113765900
1992-01-01	2.109718390000710
1993-01-01	2.425363143237510
1994-01-01	2.806694718617490
1995-01-01	3.027366915797320
1996-01-01	3.092022724032260
1997-01-01	3.262418555626460
1998-01-01	3.871775978752010
1999-01-01	4.382738927772990
2000-01-01	4.376340657342810
2001-01-01	4.601753264375580
2002-01-01	5.181406432496000
2003-01-01	4.914133082257460
2004-01-01	4.454592774629180
2005-01-01	4.411305812024770
2006-01-01	3.916979560360160
2007-01-01	3.837353424163530
2008-01-01	4.071626407493030
2009-01-01	5.055683114406800
2010-01-01	4.816527105121940
2011-01-01	4.374848241781000
2012-01-01	4.218292094127110
2013-01-01	3.892772395790010
2014-01-01	3.586970446372330
2015-01-01	3.311158843788940
2016-01-01	3.039208058336900
2017-01-01	2.768279853100740