Year annual % 1966 23.041738136077758 1967 14.866790582403965 1968 18.509129156665498 1969 10.206636020208457 1970 16.538294752927087 1971 29.578637748954566 1972 20.175306649892654 1973 13.373462444386286 1974 46.36175679473283 1975 26.328782340960988 1976 64.92585113774535 1977 19.079231024938043 1978 19.470041624977195 1979 2.550405441358489 1980 26.66371887048271 1981 35.4936496034453 1982 -41.773710998706534 1983 93.68917244041694 1984 -3.519077990377084 1985 9.126679230694887 1986 -2.0078445091203765 1987 9.408475208152106 1988 4.042331517030805 1989 4.449289846456775 1990 -11.56314434214152 1991 23.208514551924498 1992 4.8603614052283595 1993 5.72781962640605 1994 5.98352313038499 1995 7.424578642304239 1996 3.1019619736768473 1997 7.848517560311745 1998 16.756756756756758 1999 4.124095359727543 2000 10.221290949046864 2001 9.240970000463673 2002 10.338455008488964 2003 6.357003108970931 2004 4.147240120437828 2005 21.991229519116235 2006 14.893575945489971 2007 39.29978443469858 2008 19.67982924226254 2009 5.809702158016765 2010 10.509460199738738 2011 3.4013346043851285 2012 4.052808201497216 2013 8.202202060296758 2014 6.511556812350558 2015 2.9460304443647174