Year Percent 1967 35.89731 1968 47.49594 1969 39.39336 1970 40.19027 1971 47.1719 1972 45.47529 1973 74.17909 1974 158.95281 1975 111.65499 1976 69.34762 1977 67.33679 1978 80.7079 1979 75.9587 1985 211.77572 1986 122.89853 1987 85.48623 1988 108.49513 1989 96.04874 1990 93.58586 1991 96.45183 1992 72.91545 1993 84.88601 1994 102.26139 1995 94.3113 1996 90.91154 1997 77.03164 1998 59.96642 1999 57.56297 2000 56.62783 2001 49.49583 2002 68.33033 2003 56.6954 2004 49.61428 2005 55.54119 2006 59.39039 2007 52.43245 2008 40.7848 2009 43.74349 2010 42.49982 2011 49.45682 2012 46.56763 2013 55.23639 2014 42.67243 2015 44.16712 2016 35.85705 2017 40.99915 2018 44.58068 2019 46.63761 2020 54.44203 2021 33.69074