Table 1.5 (b) features estimated annual deadweight
ton-miles (dwt-miles), which are calculated by
multiplying the number of voyages between each port
by the distance and individual vessel dwt. Therefore,
unlike cargo ton-miles, dwt-miles measure total annual
vessel activity not only when the ship is laden but also
when in ballast. Thus, this measure is not equivalent
to measuring the potential ton-mile capacity, as data
!n table 1.5 (b) reflect voyages actually made, and
do not account for unused ship supply capacity
(for example, ships that are laid up, waiting or out
of service). Therefore, the dwt-mile data presented
in table 1.5 (b) do not measure supply or determine
utilisation. The dwt-miles to cargo ton-miles ratio over
the 2008-201 1 period is around 2, reflecting, in paft,
the dlfference between the two measures,
Bearing in mind these dffierences, the evolution of dwtmiles
as shown in table 1.5 (b) appears to be in line
with the trends obsenved in cargo ton-miles as shown
in table 1.5 (a). The performance of dwt-miles clearly
highlights the impact of the 20Og downturn when global
trade collapsed, as well as the strong rebound in trade
volumes recorded since 2010. Bapid growth in gas trade
and, more specifically, the recent surge in LNG trade
have been key drivers of growth in dwt-miles over the
2010-201 1 period. Table 1 .5 (b) also shows the relatve
resilience of dry bulk trade owing to the booming Asian
demand lor commodities such as iron ore and coal.