Seaborne shipping is the most important mode of transport in international trade. In comparison to other modes of freight transport, like truck, aircraft, train and pipeline, ships are preferred for moving large amounts of cargo over long distances, because shipping is more cost-efficient and environmentally friendly. Reviews of maritime transport provided by the United Nations Conference on Trade and Development (UNCTAD) show that about 80% of international trade is transported (at least partly) over sea. In 2013, containerised cargo is with a total of 1.5 billion tons responsible for over 15% of all seaborne trade, which resulted in a world container port throughput of more than 650 million TEU (twenty-foot equivalent units).