Year kt 1960 4202.382 1961 7044.306999999999 1962 9948.570999999998 1963 4195.047999999998 1964 8320.422999999997 1965 9387.519999999997 1966 8764.13 1967 10447.282999999998 1968 10238.263999999997 1969 10986.331999999997 1970 14590.992999999995 1971 18907.051999999996 1972 19475.436999999994 1973 23930.841999999997 1974 21979.997999999992 1975 24191.199 1976 26571.082 1977 29812.710000000003 1978 27704.184999999998 1979 27432.827000000005 1980 27220.141 1981 21671.97 1982 18070.976000000002 1983 14051.944000000003 1984 13960.269000000002 1985 14323.302000000001 1986 12999.515000000005 1987 14125.284000000001 1988 13842.925000000001 1989 15581.083000000002 1990 17458.587000000003 1991 17854.623000000007 1992 19057.399 1993 18888.717000000004 1994 18268.994000000002 1995 19460.769000000004 1996 21026.578000000005 1997 19431.433000000005 1998 19926.478000000003 1999 21785.647000000004 2000 22119.344000000005 2001 22240.355000000003 2002 21110.919000000005 2003 22280.692 2004 21572.961 2005 22005.667 2006 23164.439000000002 2007 22794.071999999996 2008 24117.859 2009 21466.618000000002 2010 22313.695 2011 21242.931 2012 21026.578 2013 22885.747 2014 21110.919 2015 21114.586 2016 22504.378999999994