Year	million ton-km
1974	2.2000000477
1975	4
1976	6.8000001907
1977	8.1999998093
1978	9.6000003815
1979	14
1980	26.2000007629
1981	21.3999996185
1982	21.6000003815
1983	23.7999992371
1984	30.7000007629
1985	32.5999984741
1986	48.5999984741
1987	68.0999984741
1988	96.1999969482
1989	117.8000030518
1990	145.1000061035
1991	184.3999938965
1992	267
1993	365.3999938965
1994	465.8999938965
1995	557.200012207
1996	651.299987793
1997	809.4000244141
1998	902
1999	1129.6999511719
2000	1456.349
2001	1631.164
2002	2079.338
2003	2772.739
2004	3733.658
2005	4641.933
2006	5735.78
2007	6538.02
2008	9289.48
2009	8959.601
2010	9774.15041487849
2011	10434.8491894756
2012	12032.543632735
2013	14082.25474
2014	15527.192868
2015	15962.692
2016	16138.874
2017	16616.24461
2018	15962.90443
2019	14765.5995814573
2020	12171.5568
2021	15300.72918