Year Percent 1979 123.03873 1980 68.39841 1981 47.86056 1982 22.53837 1983 22.25701 1984 51.41368 1985 50.76889 1986 82.36794 1987 48.71585 1988 45.19657 1989 43.18225 1990 42.24341 1991 32.94456 1992 43.78099 1993 30.98002 1994 27.37424 1995 25.21746 1996 24.64288 1997 26.49351 1998 28.44142 1999 21.97325 2000 28.28563 2001 31.50027 2002 30.2913 2003 25.68922 2004 32.79565 2005 27.51621 2006 32.31913 2007 43.06894 2008 36.0457 2009 35.69124 2010 38.08531 2011 29.47634 2012 38.54045 2013 43.33829 2014 46.17014 2015 48.64137 2016 51.94319