Year	million ton-km
1970	4.1999998093
1971	3.2999999523
1972	3.2999999523
1973	3.5
1974	3.5
1975	7.6999998093
1976	9.5
1977	17.5
1978	20.6000003815
1979	17.5
1980	10.8000001907
1981	11
1983	7.0999999046
1984	9.6999998093
1985	8.5
1986	5.5999999046
1987	3
1988	4
1990	70.4000015259
1991	0.6999999881
1992	0.8000000119
1993	2.7999999523
1994	2.5
2010	0
2011	0
2012	0
2013	0
2018	0
2019	0