Year	million ton-km
1970	1.7999999523
1971	1.7000000477
1972	1.7000000477
1973	4.1999998093
1974	6.9000000954
1975	7.1999998093
1976	9
1977	10.1000003815
1978	10.6999998093
1979	11.6000003815
1980	12.1000003815
1981	5.4000000954
1982	6
1983	7
1984	7.6999998093
1985	7.3000001907
1986	16.2000007629
1987	21.6000003815
1988	11.8000001907
1989	17
1990	12.8999996185
1991	11.3000001907
1992	34.5999984741
1993	36.9000015259
1994	39.0999984741
1995	52.5999984741
1996	46.2999992371
1997	23.1000003815
1998	16.5
1999	33.9000015259
2000	36.505
2001	32.648
2002	32.837
2003	36.254
2004	40.474
2005	43.118
2006	51.04
2007	45.891999999999996
2008	46.821000000000005
2009	41.803
2010	14.638193367
2011	22.7181682625349
2012	23.5445337567467
2013	12.415236
2014	11.895
2015	7.44532026283296
2016	5.1483685301
2017	5.6883385341
2018	0.85847
2019	0.0755
2021	25.8138525