Year annual % 1964 26.07415730337106 1965 16.478619681657143 1966 25.27697863744869 1967 40.749517504214154 1968 31.771475187891348 1969 11.950472552441939 1970 22.486174844099192 1971 7.753527823940211 1972 21.486995475718317 1973 37.83269124931204 1974 32.92072948360659 1975 10.024752970956893 1976 38.05832276102074 1977 59.2366311570511 1978 54.27860086870287 1979 4.9918882352847485 1980 62.73705388428138 1981 51.995667962111156 1982 74.87829393703561 1983 1113.0046592245596 1984 -81.70201045223648 1985 31.738214025032157 1986 57.31267801892572 1987 94.30074707787784 1988 131.49659247839787 1989 67.40596062104589 1990 195.38650597263424 1991 2388.5671617312205 1992 3794.4489546205104 1993 2853.124915926657 1994 6968.922518159806 1995 357.6323059190639 2001 41.42720186182681 2002 38.44250163099156 2003 29.735712325652734 2004 81.85423550275738 2005 23.34078444037476 2006 56.53031673401049 2007 50.586762528240016 2008 55.0502772933809 2009 56.214045918776435 2010 34.764283862489634 2011 21.496857051521832 2012 20.670607885718752 2013 18.74037715095977 2014 14.660309823612543 2015 9.385459484265473 2016 21.774899833106975 2017 34.26826216279341 2018 35.801481454545