Year	million ton-km
1970	1.2000000477
1971	1.2999999523
1972	1.2999999523
1973	1.2999999523
1974	1.3999999762
1975	0.6999999881
1976	0.8000000119
1977	0.8000000119
1978	0.8000000119
1979	0.8000000119
1980	0.8000000119
1981	2
1982	2.2000000477
1983	2.2000000477
1984	2.2999999523
1985	2.2999999523
1986	2.4000000954
1987	2.5
1988	2.5999999046
1989	2.7999999523
1990	2.7999999523
1991	2.7999999523
1992	3
1993	3
1994	3
1995	3.0999999046
1996	3.2999999523
1997	3.2999999523
1998	3.2999999523
1999	2.2000000477
2000	2.323
2001	1.603
2010	0.925987427
2011	1.23149676596269
2012	0.941436372233282
2013	0
2014	0
2018	0.100011
2019	0.0475892117738182
2020	0.10855
2021	0.022018