Year	million ton-km
1975	4.9000000954
1976	5.3000001907
1977	5.4000000954
1978	7.1999998093
1979	9.6999998093
1980	8.6999998093
1981	9.1999998093
1982	10.3999996185
1983	15.3000001907
1984	12.3999996185
1985	9.1000003815
1986	10.3000001907
1987	8.6000003815
1988	10.1999998093
1989	10.1000003815
1990	9.1000003815
1991	9.3999996185
1992	8.6000003815
1993	9.8999996185
1994	11.3000001907
1995	5.5
1996	5.4000000954
1997	5.1999998093
1998	5.9000000954
1999	6.5999999046
2000	7.164
2001	6.885
2002	7.095
2003	6.627
2004	5.344
2005	4.928
2006	5.196
2007	5.778
2008	6.743
2009	5.827
2010	6.14
2011	8.075
2012	4.92238023654571
2013	5.882496
2014	5.36650299100094
2015	4.86366165923809
2016	4.37
2017	3.557
2018	4.775
2019	6.347
2020	2.423532
2021	2.629