Year	kt
1960	4635.088
1961	5001.788
1962	5269.479
1963	5845.198
1964	6369.579
1965	7429.342
1966	7748.371
1967	8045.398
1968	8265.418
1969	8797.133
1970	8577.113
1971	9820.226
1972	10623.299
1973	11793.072
1974	11987.423
1975	11800.406
1976	11540.049
1977	11723.399
1978	10461.951
1979	10153.923
1980	10883.656
1981	9856.896
1982	9871.564
1983	8973.149
1984	8969.482
1985	10428.948
1986	10703.973
1987	11606.055
1988	11353.032
1989	11950.753
1990	9629.542
1991	9908.234
1992	10780.98
1993	11067.006
1994	12262.448
1995	13369.882
1996	14374.64
1997	15078.704
1998	15474.74
1999	16153.135
2000	16347.486
2001	16138.467
2002	16571.173
2003	17740.946
2004	17781.283
2005	17638.27
2006	17623.602
2007	17990.302
2008	17902.294
2009	17597.933
2010	17102.888
2011	17077.219
2012	18107.646
2013	17927.963
2014	18390.005
2015	19196.745
2016	19479.104