Year	million ton-km
1970	2.4000000954
1971	1.8999999762
1972	1.7000000477
1973	2.2999999523
1974	2.5999999046
1975	2.5
1976	3.5
1977	4
1978	3.7999999523
1979	5
1980	4.0999999046
1981	4.1999998093
1982	3.2000000477
1983	3.2999999523
1984	3.5
1985	4.4000000954
1986	4
1987	4.6999998093
1988	4.9000000954
1989	5.5
1990	4.8000001907
1991	5.5999999046
1992	6.4000000954
1993	7.3000001907
1994	11.8000001907
1995	13.6999998093
1996	9.6999998093
1997	9
1998	11.1999998093
1999	10.5
2000	14.286
2001	13.781
2002	12.014
2003	11.979
2004	11.62
2005	11.106
2006	11.661
2007	11.894
2008	11.763
2009	6.672
2010	6.733
2011	6.352
2012	5.266
2013	3.541
2014	3.422
2015	3.352
2016	2.442
2017	2.63621
2018	5.14323
2019	6.727273
2020	2.903530909
2021	2.75098