In tonnage terms, the amount of oil transported by sea increased from 1,600 million tonnes in 1992 to over 2,400 million tonnes in 2008. Over 34,000 million tonnes was carried over the 16 year period. By contrast, the number of major oil spills during the same period shows a steady reduction. Although serious accidents occasionally occur - the loss of the 'Erika' and 'Prestige' being recent high profile examples - the trend shows a continuing improvement, both in quantity and frequency of oil spills each year.