Year	million ton-km
1975	0.1000000015
1976	0.200000003
1977	0.200000003
1978	0.200000003
1979	0.3000000119
1980	0.3000000119
1981	0.400000006
1982	0.400000006
1983	0.400000006
1984	0.400000006
1985	1.2999999523
1986	1.3999999762
1994	0.200000003
1995	2.9000000954
1996	6.8000001907
1997	6.5999999046
1998	10.3000001907
1999	11.8999996185
2000	13.17
2001	0.008
2002	0.009
2003	0.009
2004	0.011
2005	0.013
2006	0.013
2007	0.013
2008	0.013
2009	0.013
2015	5.87870598184376
2016	6.872800012
2017	7.745645613
2018	0
2019	0
2020	2.28629
2021	1.7375017