Year % 1989 31.92 1990 18.95 1991 13.21 1992 13.61 1993 12.47 1994 12.23 1995 9.52 1996 12.91 1997 12.64 1998 13.05 1999 8.95 2000 12.93 2001 12.41 2002 7.15 2003 12.31 2004 5.18 2005 5.24 2006 4.53 2007 4.78 2008 4.33 2009 4.4 2010 5.9 2011 5.56 2012 5.52 2013 6.16 2014 4 2015 5.3 2016 5.68 2017 3.5