Year	million ton-km
1970	5.9000000954
1971	7.1999998093
1972	8.1000003815
1973	8.3999996185
1974	10.8999996185
1975	11.6000003815
1976	13.1999998093
1977	13.1999998093
1978	14.8000001907
1979	17.2999992371
1980	18.2000007629
1981	21.3999996185
1982	21.3999996185
1983	19.1000003815
1984	17.7999992371
1985	18.3999996185
1986	16.6000003815
1987	16.2999992371
1988	15.8999996185
1989	18.1000003815
1990	17.7000007629
1991	16.1000003815
1992	15.1999998093
1993	14.3000001907
1994	14.5
1995	15.3000001907
1996	16.5
1997	15.3000001907
1998	13.6000003815
1999	13.8000001907
2000	12.292
2001	7.364
2010	15.376963961
2011	2.70860361698403
2012	0
2013	4.563948
2014	4.71912
2015	0.983368072842825
2016	1.20223033825879
2017	5.41940666666667
2018	4.16026898442412
2019	9.166862
2020	4.317833
2021	4.028365