Membership of the Group is open to member countries of the United Nations or its specialised agencies or of the WTO, which consider themselves substantially interested in the production, consumption or trade in lead and/or zinc. In addition, several intergovernmental and non governmental organisations, all substantially interested in lead and zinc, are officially accredited Observers. The Group’s member countries (listed below) currently account for over 85% of world production and usage of both lead and zinc.