Historically Yes, OPEC believes that oil demand will continue to grow strongly and oil will remain the world's single most important source of energy for the foreseeable future. The OWEM reference case sees oil's share of the world fuel mix falling slightly from over 41 per cent today to just over 39 per cent in 2020. However, oil will still be the world's single largest source of energy. The reduction in oil's market share is largely due to the stronger growth enjoyed by other forms of energy, particularly natural gas (see the table below).