Year	Percent
1962-01-01	0.448367270615522
1963-01-01	0.535856280556365
1964-01-01	0.489099230491090
1965-01-01	0.424433798396839
1966-01-01	0.465834921955750
1967-01-01	1.349085650824980
1968-01-01	0.956744732340411
1969-01-01	0.523998858466439
1970-01-01	0.431555236639266
1971-01-01	0.533069956428555
1972-01-01	0.709575317865178
1973-01-01	0.781360675454760
1974-01-01	1.666523777275220
1975-01-01	3.103750985305930
1976-01-01	3.090683224670200
1977-01-01	3.009055966126640
1978-01-01	2.889837904205760
1979-01-01	2.528004043173870
1980-01-01	2.469314636007730
1981-01-01	3.487884674012230
1982-01-01	4.983604534901980
1983-01-01	6.131379618121650
1984-01-01	6.139421354341290
1985-01-01	6.193343123167480
1986-01-01	5.929548528989500
1987-01-01	5.891680737669780
1988-01-01	5.878985226738900
1989-01-01	5.311516983712730
1990-01-01	4.817337054472960
1991-01-01	5.569215367244570
1992-01-01	6.621124917683560
1993-01-01	7.869413456965040
1994-01-01	8.401136494394510
1995-01-01	8.126454224911970
1996-01-01	8.863040083717870
1997-01-01	9.817107548737640
1998-01-01	9.201704617884420
1999-01-01	8.414572772086440
2000-01-01	7.755578147350240
2001-01-01	7.836030807859470
2002-01-01	8.653862509461660
2003-01-01	9.637082821977020
2004-01-01	9.793686437665200
2005-01-01	11.167683288314200
2006-01-01	10.252724940747800
2007-01-01	8.661529717481270
2008-01-01	7.527764134975300
2009-01-01	7.743155029925620
2010-01-01	6.967637227225480
2011-01-01	5.827424071581710
2012-01-01	5.380757115948400
2013-01-01	5.231961970561780
2014-01-01	4.981591473404010
2015-01-01	4.624955221153000
2016-01-01	4.122732888477280
2017-01-01	3.746630734962180