Year annual % 1977 15.6365217842167 1978 16.4830693049293 1979 19.6096605730897 1980 4.22610021946809 1981 -1.05140397943869 1982 7.28603418655803 1983 -1.4160557429492 1984 5.31693301209593 1985 1.58797484563028 1986 -9.63850181477753 1987 1.96996323615168 1988 -8.04452556075518 1989 -8.36935717645076 1990 -13.4624088920027 1991 -17.8883090275404 1992 21.0459676650265 1993 -6.40638940570486 1994 -2.81967262138035 1995 -3.97750523668722 1996 4.98024225341985 1997 3.11177111139484 1998 4.99623867453684 1999 0.7423001516498 2000 12.228443940203 2001 3.24632615544944 2002 -2.87738456949192 2003 -1.23813440688325 2004 7.67850451683631 2005 10.8375522855422 2006 1.53808827051223 2007 5.04815432640568 2008 3.37587467356492 2009 -7.50325992491003 2010 -12.8243063125074 2011 1.72464400842446 2012 4.19168558224416 2013 3.38853603403737 2014 -5.21857408140835 2015 0.171055809329502 2016 -2.7546695058996 2017 1.5279629562306 2018 -2.96121585408585