Year kt 1960 39049.883 1961 41503.106 1962 44865.745 1963 46948.601 1964 47040.276 1965 45800.83 1966 51899.051 1967 53769.221 1968 64033.154 1969 69478.649 1970 78316.119 1971 87124.253 1972 97806.224 1973 115459.162 1974 124938.357 1975 129811.8 1976 132316.361 1977 135403.975 1978 145590.901 1979 154655.725 1980 150335.999 1981 135638.663 1982 133302.784 1983 125840.439 1984 122162.438 1985 127618.934 1986 142492.286 1987 145660.574 1988 147772.766 1989 151703.79 1990 150592.689 1991 155176.439 1992 159573.172 1993 167174.863 1994 176287.358 1995 188043.76 1996 206719.791 1997 218666.877 1998 229066.489 1999 233037.85 2000 234046.275 2001 238820.709 2002 231516.045 2003 219594.628 2004 226484.921 2005 232099.098 2006 230844.984 2007 240217.836 2008 253000.998 2009 251145.496 2010 273884.563 2011 289139.283 2012 309527.803 2013 325988.966 2014 342754.49 2015 317125.827 2016 296990.33