Year	million ton-km
1970	2.2000000477
1971	2.4000000954
1972	2.9000000954
1973	2.4000000954
1974	1.8999999762
1975	1.1000000238
1976	6.1999998093
1977	16.2000007629
1978	20
1979	23.7000007629
1980	18.8999996185
1981	17.2000007629
1982	19
1983	17.8999996185
1984	25.5
1985	24.6000003815
1986	26.7999992371
1987	30.3999996185
1988	26.6000003815
1989	33
1990	34.2999992371
1991	33.9000015259
1992	33
1993	32.2000007629
1994	35.4000015259
1995	36.2000007629
1996	35.4000015259
1997	35.7000007629
1998	38.2000007629
1999	40.7000007629
2000	43.118
2001	39.982
2002	40.887
2003	44.208
2004	49.159
2005	47.964
2006	47.815
2007	49.376
2008	47.549
2009	38.312
2010	36.2141
2011	16.9749
2012	9.1093
2013	11.592996
2014	6.588588
2015	0.23060058
2016	0.285895446767606
2017	0.34031950189
2018	0.021
2019	0.14
2020	0.328962
2021	0.105655573