The 2010 guidelines for monitoring the worldwide
average sulphur content of fuel oils supplied for use
on board ships (IMO, 2010, annex I) provide for the
calculation of a rolling average of the sulphur content
for a three-year period. The rolling average based on
the average sulphur contents calculated for 2011,
2012, and 2013 is 2.53 per cent for residual fuel and
0.14 per cent for distillate fuel (IMO 2012b, 2013g,
2014c).