The IMO has nearly 160 members and is headed by a secretary-general, who serves a four-year term and oversees a Secretariat staff of approximately 300—one of the smallest UN agency staffs. All members are represented in the Assembly, the IMO's primary policy-making body, which meets once every two years. The Council, originally consisting of 24 members but subsequently raised to 32 (a 1993 resolution proposed to increase membership to 40, though it must be ratified by two-thirds of IMO members before it goes into effect), meets twice annually and is responsible for governing the organization between Assembly sessions. Membership on the Council is divided among three groups: (1) the 8 countries with the “largest interest” in providing international shipping services; (2) the 8 countries with the largest interest in providing international seaborne trade; and (3) 16 countries with a “special interest” in maritime transport, selected to ensure equitable geographic representation. Safety proposals are submitted to the Assembly by the Maritime Safety Committee, which meets annually. There are a number of other committees and subcommittees dealing with specific issues, such as the environment, legal issues, the transport of dangerous goods, radio communications, fire protection, ship design and equipment, lifesaving appliances, and cargoes and containers. The IMO's Global Maritime Distress and Safety System, an integrated communications system using satellites and terrestrial radio communications to provide aid to ships in distress even in cases where the crew is unable to send a manual distress signal, was established in 1992 and became fully operational in 1999.