![World Seaborne Trade by Cargo Type, 1970-2018 | Port Economics, Management and Policy](https://i0.wp.com/porteconomicsmanagement.org/wp-content/uploads/seaborne_trade.png?resize=900%2C422&ssl=1)
Source: UNCTAD Review of Maritime Transport, various years. Major dry bulks are iron ore, grain, and coal.
Weight-wise, raw materials dominate maritime trade as they are ponderous and carried over long distances. Oil, iron ore, coal, and grain accounted for 28% of the ton-miles carried by maritime shipping, while other dry cargoes, which include containers, accounted for 40%. Oil is the most significant commodity, with 25% of ton-miles in 2018, but this share is significantly lower than in 1970 when it accounted for 60% of global ton-miles.