Year	Percent
1960-01-01	1.589403973350620
1961-01-01	2.157971925583790
1962-01-01	4.315615655790700
1963-01-01	2.962903485003120
1964-01-01	3.838174273930410
1965-01-01	4.444444444444450
1966-01-01	4.173891503591770
1967-01-01	3.773927145376090
1968-01-01	4.151643358215590
1969-01-01	3.616856514173080
1970-01-01	5.801545520700470
1971-01-01	6.350420811017610
1972-01-01	6.562347717876170
1973-01-01	8.494158568095050
1974-01-01	14.379727813786300
1975-01-01	12.273305005715200
1976-01-01	10.037946113958900
1977-01-01	10.655944226156400
1978-01-01	8.532173636625150
1979-01-01	9.377799150379890
1980-01-01	12.907346468855700
1981-01-01	12.897874136105400
1982-01-01	10.446648715769800
1983-01-01	8.540159730576960
1984-01-01	6.707588009912400
1985-01-01	5.849014035834970
1986-01-01	4.203480141446570
1987-01-01	4.293598655907840
1988-01-01	5.104721899329020
1989-01-01	5.700014690759820
1990-01-01	6.102895230160360
1991-01-01	5.615234374999730
1992-01-01	3.571455955891650
1993-01-01	3.601862688702600
1994-01-01	2.675997105766800
1995-01-01	2.730935891427690
1996-01-01	2.389173110348140
1997-01-01	2.006907006142200
1998-01-01	1.843357607723900
1999-01-01	1.938986726199310
2000-01-01	3.046505803634200
2001-01-01	2.921774342997420
2002-01-01	2.443694884593300
2003-01-01	2.099846885340290
2004-01-01	2.205046746296120
2005-01-01	2.299316566971960
2006-01-01	2.332839076248300
2007-01-01	2.354252398180580
2008-01-01	4.006225282229830
2009-01-01	0.628230843146469
2010-01-01	1.806637599658580
2011-01-01	3.285394533832010
2012-01-01	2.450731140660450
2013-01-01	1.421677443938770
2014-01-01	0.536227438176895
2015-01-01	0.174232080103779