Of the more than 1,000 ports on all the coasts of the world there are at present about 140 which each handle more than 5 million tons of foreign trade cargoes annually.
Ngaphezu kwamazibuko enqanawa eliwaka kuwo onke amanxweme omhlaba ngoku sithethayo kukho malunga nekhulu elinashumi eliphatha ngaphezu kwezigidi ezintathu zeetoni zemithwalo yamazwe angaphandle ngonyaka.