Year	million ton-km
1970	6.9000000954
1971	7.1999998093
1972	7.6999998093
1973	8.6999998093
1974	9
1975	7.5999999046
1976	6.6999998093
1977	6.5999999046
1978	6.1999998093
1979	17.2999992371
1980	19.7999992371
1981	21
1982	19.7000007629
1983	19.2999992371
1984	22.1000003815
1985	20.1000003815
1986	19.2000007629
1987	21
1988	23.3999996185
1989	29
1990	30.2000007629
1991	26.1000003815
1992	27.5
1993	27.1000003815
1994	23.6000003815
1995	31.5
1996	25.2000007629
1997	29
1998	28.8999996185
1999	27.8999996185
2000	27.323
2001	10.206
2002	10.863
2003	9.72
2004	12.657
2005	15.363
2006	18.773
2007	23.941
2008	12.188
2009	14.27
2010	23.775
2011	21.2715163636364
2012	24.97688
2013	34.55841
2014	31.07096
2015	25.62026
2016	11.96217
2017	15.02506
2018	16.24747
2019	16.18255
2020	5.384373332
2021	2.719098