Year	million ton-km
1976	0.1000000015
1977	0.1000000015
1978	0.200000003
1979	0.200000003
1980	0.200000003
1981	0.3000000119
1982	0.3000000119
1983	0.3000000119
1984	0.400000006
1985	0.400000006
1986	0.3000000119
1987	0.5
1988	0.5
1989	0.5
1990	0.6000000238
1991	0.6999999881
1992	0.8000000119
1993	0.8000000119
1994	0.8000000119
1995	0.8000000119
1996	0.8000000119
1997	0.6000000238
1998	0.400000006
1999	0.6000000238
2000	0.64
2001	0.366
2002	0.368
2003	0.406
2004	0.834
2005	1.506
2006	1.79
2007	1.611
2008	1.574
2009	1.426
2010	1.641
2011	1.95548997224695
2012	2.17938738529673
2013	1.941924
2014	1.882368
2018	0.048636
2019	0.049965
2020	0.031316
2021	0.016159056