Year	million ton-km
1970	6.1999998093
1971	7.5999999046
1972	5.9000000954
1973	5.8000001907
1974	6
1975	5.5999999046
1976	5.1999998093
1977	5.5
1978	5.9000000954
1979	7.8000001907
1980	9.1999998093
1981	9.6999998093
1982	9.1999998093
1983	8.8000001907
1984	8.6000003815
1985	10.3000001907
1986	8.8000001907
1987	7.3000001907
1988	5.8000001907
1989	5.8000001907
1990	6.3000001907
1991	5
1992	6.5
1993	10.5
1994	17.7000007629
1995	28.5
1996	29.2999992371
1997	34.9000015259
1998	37
1999	39.9000015259
2000	50.852
2001	32.294
2002	25.151
2003	28.37
2004	23.996
2005	21.429
2006	20
2007	27.161
2008	11.755
2009	9.804
2010	5.60895570713066
2011	5.85295
2012	0.467678756906942
2013	0
2018	0
2019	0