Year annual % 1961 9.018830525272548 1962 11.181818181818182 1963 20.686835650040884 1964 8.401084010840108 1965 11.75 1966 18.456375838926174 1967 14.258734655335223 1968 15.710743801652892 1969 5.90314977501607 1970 6.009104704097116 1971 14.06304672837739 1972 40.60460706118579 1973 35.070808044745924 1974 43.54919236417034 1975 81.88569616498052 1976 66.5286885706894 1977 53.86257252666346 1978 27.383534101285385 1979 13.697855908357012 1980 17.359847112830064 1981 32.999216146099 1982 20.19607386219097 1983 10.742123285734712 1984 6.023196440294696 1985 1.1418176614341384 1986 9.218621179428435 1987 4.11406911362068 1988 6.416202502567833 1989 0.8733491895829948 1990 4.5820550758316685 1991 14.553911556560415 1992 2.0546915411036646 1993 3.380838051026406 1994 2.985565405389924 1995 3.35659970734372 1996 7.256991920061336 1997 5.210444059034862 1998 3.6310346409727003 1999 6.833958016475767 2000 4.465956135467955 2001 5.087299207063277 2002 15.198385621351257 2003 8.49234471316397 2004 17.251988433396782 2005 13.241010792381141 2006 20.408390648326822 2007 20.141374570062908 2008 17.959669556063698 2009 10.810241726215569 2010 5.172335088191353 2011 13.260447982153082 2012 16.48947816027958 2013 8.351987222167878 2014 11.823261584106145 2015 2.9048048129634028 2016 0.5477072445128036 2017 0.15085308580609633