Botswana Exports of bitumen and asphalt (natural), bituminous or oil shale, tar sands to Namibia was US$25 during 2020, according to the United Nations COMTRADE database on international trade. Botswana Exports of bitumen and asphalt (natural), bituminous or oil shale, tar sands to Namibia - data, historical chart and statistics - was last updated on May of 2024.