Year	million ton-km
1970	5.9000000954
1971	7.3000001907
1972	8.1999998093
1973	8.5
1974	11.1000003815
1975	11.8000001907
1976	13.5
1977	13.3999996185
1978	15.1000003815
1979	17.5
1980	18.3999996185
1981	21.3999996185
1982	21.5
1983	20.2000007629
1984	19
1985	20
1986	17.7000007629
1987	16.8999996185
1988	16.5
1989	18.6000003815
1990	18.3999996185
1991	16.7999992371
1992	15.8000001907
1993	14.8999996185
1994	15.1000003815
1995	16
1996	17.2000007629
1997	15.6000003815
1998	13.8000001907
1999	13.6999998093
2000	12.273
2001	7.364
2002	0
2003	0
2010	1.86657368035625
2011	1.43488058350513
2012	1.59781520479946
2013	2.384004
2014	1.992936
2015	4.36693937329617
2016	4.52411089880374
2017	4.59716061898045
2018	4.59716061898045
2019	4.15110874340146