Year	Percent
1960-01-01	5.81407628204986
1961-01-01	8.28319045648717
1962-01-01	4.69709395062471
1963-01-01	26.35543552504660
1964-01-01	17.07243521645540
1965-01-01	7.59068366931586
1966-01-01	16.72816827485980
1967-01-01	8.32819136425946
1968-01-01	7.44753878317766
1969-01-01	6.98166307955371
1970-01-01	6.90862275848249
1971-01-01	11.94029850746270
1972-01-01	12.44444444444440
1973-01-01	22.52964426877470
1974-01-01	23.87096774193550
1975-01-01	23.43750000000000
1976-01-01	19.83122362869200
1977-01-01	33.80281690140850
1978-01-01	17.76315789473680
1979-01-01	24.13407821229050
1980-01-01	26.55265526552660
1981-01-01	27.45376955903270
1982-01-01	24.72098214285710
1983-01-01	19.59731543624160
1984-01-01	16.16161616161610
1985-01-01	24.09017713365540
1986-01-01	18.84246042045160
1987-01-01	23.30203101113780
1988-01-01	28.10839532412330
1989-01-01	25.86755150006910
1990-01-01	29.15202108963090
1991-01-01	30.38782105800300
1992-01-01	27.01063205270370
1993-01-01	22.44248151191450
1994-01-01	22.84623773173390
1995-01-01	20.89180238314730
1996-01-01	20.79755987347490
1997-01-01	18.47002712054610
1998-01-01	18.67698137038210
1999-01-01	10.87368631102830
2000-01-01	9.22534683164604
2001-01-01	7.96556174992444
2002-01-01	6.35150775179012
2003-01-01	7.12978797192092
2004-01-01	5.90402196845384
2005-01-01	5.05101610591109
2006-01-01	4.29342591106120
2007-01-01	5.54438490326428
2008-01-01	6.99688257706963
2009-01-01	4.20251827367056
2010-01-01	2.27200261619591
2011-01-01	3.41503189601417
2012-01-01	3.16930259882815
2013-01-01	2.01699309187360
2014-01-01	2.89883811454339
2015-01-01	4.98982905677885
2016-01-01	7.51346059716106
2017-01-01	4.31431317500060