Year % 1985 39.9655239888964 1986 26.3591384058586 1987 32.6655350973518 1988 21.2134249729057 1989 36.009133634171 1990 48.8691791893508 1991 28.5754178909029 1992 23.9705261388324 1993 24.3458278419054 1994 20.3396521773457 1995 18.1595558966592 1996 17.3678567329936 1997 15.670265400513 1998 20.1695011436128 1999 12.6231518368615 2000 14.8433912347788 2001 11.8910098561076 2002 7.75807289652374 2003 6.17877873086097 2004 5.12700362788107 2005 6.67787900981346 2006 7.99948207856606 2007 8.67125848644778 2008 13.261771366415 2009 7.25063476884463 2010 4.75482680518703 2011 9.03015252269429 2012 10.0572624433615 2013 9.26187678192101 2014 8.09805824839012 2015 5.51492732291402 2016 5.58839657725206 2017 4.55285507889072 2018 4.17801925025561