Year	million ton-km
1970	5.8000001907
1971	7.0999999046
1972	8
1973	8.8000001907
1974	11.3000001907
1975	12
1976	13.6999998093
1977	13.6000003815
1978	15.3000001907
1979	17.7999992371
1980	18.5
1981	21.5
1982	21.6000003815
1983	19.2999992371
1984	17.5
1985	18.6000003815
1986	16.6000003815
1987	16.5
1988	16.1000003815
1989	18.2000007629
1990	17.8999996185
1991	16.2999992371
1992	15.3999996185
1993	14.3999996185
1994	14.6999998093
1995	15.5
1996	16.7000007629
1997	15.5
1998	13.8000001907
1999	13.8999996185
2000	12.508
2001	7.439
2002	0.074
2003	0.083
2004	0.09
2005	0.095
2006	0.111
2007	0.099
2008	0.116
2009	0.099
2010	0.208132727142084
2011	0.13925043909506
2012	0
2013	0
2018	0
2019	0