Year	million ton-km
1970	11.3999996185
1971	13.6000003815
1972	14.1000003815
1973	14
1974	14
1975	14
1976	14
1977	24.5
1978	27.2999992371
1979	27.1000003815
1980	17.2000007629
1981	12.8000001907
1982	10.3999996185
1983	7.3000001907
1984	4
1986	2.5999999046
1987	3
1988	6.5
1989	2.5
1990	4.5999999046
1991	5.5999999046
1992	15.8000001907
1993	19.8999996185
1994	14.3000001907
1995	15
1996	15.8000001907
1997	19.2999992371
1998	47
1999	21.8999996185
2000	31.157
2001	46.884
2002	11.6
2003	4.797
2004	23.83
2005	20.8
2006	20.176
2007	21.987
2008	18.439
2009	15.291
2010	10.9670984067361
2011	14.662
2012	17.065
2013	15.65233
2014	16.40872
2015	13.873884
2016	13.155752
2017	13.765785
2018	10.73322
2019	13.107
2020	7.144167272
2021	11.25641