Year	Percent
1962-01-01	0.376557857373143
1963-01-01	0.399334378105383
1964-01-01	0.394395680788882
1965-01-01	0.301585121196727
1966-01-01	0.328517134725367
1967-01-01	0.933427613697984
1968-01-01	0.664847961348733
1969-01-01	0.405071095384747
1970-01-01	0.415231880960965
1971-01-01	0.620486423176281
1972-01-01	0.765801054361719
1973-01-01	0.880896301711828
1974-01-01	1.820638341090080
1975-01-01	3.207325256410320
1976-01-01	3.521009104684260
1977-01-01	3.659998297133760
1978-01-01	3.591352720827950
1979-01-01	3.241544395586450
1980-01-01	3.207241846818400
1981-01-01	4.241168502252550
1982-01-01	5.513571060583020
1983-01-01	6.649825468604290
1984-01-01	6.633600522409710
1985-01-01	6.734077025655770
1986-01-01	6.711503502757750
1987-01-01	6.583100289368860
1988-01-01	6.387678880006250
1991-01-01	7.033322115515300
1992-01-01	8.362602760877210
1993-01-01	9.590253860277160
1994-01-01	10.052890526987200
1995-01-01	9.434457543796050
1996-01-01	9.626020907418970
1997-01-01	10.608570313682300
1998-01-01	9.841772404229860
1999-01-01	8.868004140742340
2000-01-01	8.075689051675890
2001-01-01	7.937936595512330
2002-01-01	8.428920701248050
2003-01-01	9.201771838912260
2004-01-01	9.295144013721090
2005-01-01	10.888268107104000
2006-01-01	10.174847391138100
2007-01-01	8.796904061189880
2008-01-01	7.651986078518360
2009-01-01	7.313592911557860
2010-01-01	6.498120338074720
2011-01-01	5.583368939993080
2012-01-01	5.178039117915170
2013-01-01	4.916201575476190
2014-01-01	4.631158701500520
2015-01-01	4.220933606969420
2016-01-01	3.741523832050540
2017-01-01	3.314629376110720