Year Percent 1976 98.39331 1977 52.25144 1978 54.84523 1979 141.61782 1980 108.44539 1981 61.89375 1982 48.96324 1983 52.58243 1984 47.20735 1985 57.77371 1986 49.84259 1987 42.42978 1988 33.43535 1989 34.50616 1990 74.28298 1991 86.60044 1992 23.91679 1993 15.13676 1994 17.99759 1995 24.37265 1996 24.07375 1997 25.50909 1998 23.97567 1999 24.75783 2000 29.29131 2001 23.82553 2002 29.22204 2003 62.18022 2004 19.34838 2005 16.51247 2006 13.44157 2007 12.1937 2008 8.98671 2009 9.27321 2010 10.04256 2011 10.39235 2012 11.79089 2013 15.27946 2014 28.36172 2015 22.34194 2016 29.21796 2017 28.97232 2018 23.90737 2019 28.22633