Year	million ton-km
1970	5.8000001907
1971	7.0999999046
1972	8
1973	8.3000001907
1974	10.8000001907
1975	11.6000003815
1976	13.1999998093
1977	13.1000003815
1978	14.6999998093
1979	17.2000007629
1980	18
1981	21
1982	21
1983	18.7000007629
1984	17.3999996185
1985	18.3999996185
1986	16.5
1987	16.2999992371
1988	15.8999996185
1989	18
1990	17.7000007629
1991	16.1000003815
1992	15.1999998093
1993	14.3000001907
1994	14.5
1995	15.3000001907
1996	16.5
1997	15.3000001907
1998	13.5
1999	13.6999998093
2000	12.273
2001	7.364
2002	0
2003	0
2004	0
2005	0
2006	0
2007	0
2008	0
2009	0
2010	0
2011	3.37578055142813
2012	4.57883176764346
2013	4.47306
2014	3.578448
2015	3.09552348483269
2016	0.133149772
2017	0.041650904321273
2018	0
2019	2.091018
2020	2.573077
2021	3.312494155