Year Percent 1973 11.75382 1982 47.83226 1983 36.71874 1984 42.78287 1985 42.39601 1986 53.55217 1987 40.82782 1988 33.40288 1989 32.31637 1990 33.23478 1991 33.24034 1992 30.67282 1993 30.44596 1994 31.34349 1995 31.93957 1999 17.26554 2000 20.02914 2001 23.61355 2002 27.36742 2004 34.74998 2005 47.84686 2006 46.96744 2007 50.63685 2008 63.42803 2009 59.43731 2010 62.19234 2011 57.98272 2012 54.85989 2013 52.15815 2014 51.12324 2015 51.25031