Year annual % 1961 0.503387480698682 1962 0.904284443540121 1963 1.50851383539107 1964 1.43339916603503 1965 1.11820855898455 1966 0.761578756681416 1967 0.357150920745933 1968 0.855400622366689 1969 1.66403028759831 1970 1.64091333717161 1971 1.39118446644545 1972 1.12730743916053 1973 0.85215854436847 1974 0.635376611352909 1975 1.0317895654317 1976 1.45465596405477 1977 1.31954350368758 1978 1.17815549713255 1979 1.05270045134303 1980 0.897798647808138 1981 0.765272314611162 1982 1.05365832516093 1983 1.48316192992406 1984 1.49669413261499 1985 1.39828194947668 1986 1.25566519241492 1987 1.12151982573854 1988 1.01852420074943 1989 0.921850215615285 1990 0.831034299140832 1991 0.771849528449064 1992 0.749702002240685 1993 0.744123269256896 1994 0.735427307440948 1995 0.73005823579243 1996 0.749991648586953 1997 0.781953204764374 1998 0.751051413609378 1999 0.572730386196825 2000 0.218936549624527 2001 -0.0647059752351783 2002 -0.178929555681925 2003 -0.216376703381685 2004 -0.24786231551975 2005 -0.295136676013591 2006 -0.405287997089734 2007 -0.589029493886293 2008 0.122477835833443 2009 1.6775209368822 2010 2.36977191505581 2011 2.28545620835272 2012 2.19981191992032 2013 2.06780986239305 2014 1.91520497126224 2015 1.78404621981199 2016 0.842469530267675 2017 -0.0728597482140499 2018 -0.0405005878121066 2019 0.0135020185722688 2020 -0.302883026724653 2021 -0.641236845621864 2022 -0.593262624459316 2023 -0.472749142011553