1,000 tons, totaling 1.96 billion tons. Such ships carried 11 billion tons of cargo in 2018, a sum that grew by 2.7% over the previous year. In terms of tonnage, 29% of ships were tankers, 43% are bulk carriers, 13% container ships and 15% were other types. In 2008, there were 1,240 warships operating in the world, not counting small vessels such as patrol boats. The United States accounted for 3 million tons worth of these vessels, Russia 1.35 million tons, the United Kingdom 504,660 tons and China 402,830 tons. The 20th century saw many naval engagements during the two world wars, the Cold War, and the rise to power of naval forces of the two blocs. The world's major powers have recently used their naval power in cases such as the United Kingdom in the Falkland Islands and the United States in Iraq. The size of the world's fishing fleet is more difficult to estimate. The largest of these are counted as commercial vessels, but the smallest are legion. Fishing vessels can be found in most seaside villages in the world. As of 2004, the United Nations Food and Agriculture Organization estimated 4 million fishing vessels were operating worldwide. The same study estimated that the world's 29 million fishermen caught of fish and shellfish that year. Types of ships Because ships are constructed using the principles of naval architecture that require same structural components, their classification is based on their function such as that suggested by Paulet and Presles, which requires modification of the components. The categories accepted in general by naval architects are: High-speed craft – Multihulls including wave piercers, small-waterplane-area twin hull (SWATH), surface effect ships and hovercraft, hydrofoil, wing in ground effect craft (WIG). Off shore oil vessels – Platform supply vessel, pipe layers, accommodation and crane barges, non and semi-submersible drilling rigs, production platforms, floating production storage and offloading units. Fishing vessels Motorised fishing trawlers, trap setters, seiners, longliners, trollers & factory ships. Traditional sailing and rowed fishing vessels and boats used for handline fishing Harbour work craft Cable layers Tugboats, dredgers, salvage vessels, tenders, Pilot boats. Floating dry docks, floating cranes, lightership. Dry cargo ships – tramp freighters, bulk carriers, cargo liners, container vessels, barge carriers, Ro-Ro ships, refrigerated cargo ships, timber carriers, livestock & light vehicle carriers. Liquid cargo ships – oil tankers, liquefied gas carriers, chemical carriers. Passenger vessels Liners, cruise and