| 1980 | 2011 | |
| 1 | Soviet Union | Saudi Arabia |
| 2 | Saudi Arabia | Russia |
| 3 | USA | USA |
| 4 | Iraq | Iran |
| 5 | Venezuela | China |
| 6 | Mexico | Canada |
| 7 | China | UAE |
| 8 | Nigeria | Mexico |
| 9 | Libya | Kuwait |
| 10 | Canada | Iraq |
| 11 | Kuwait | Venezuela |
| 12 | UAE | Nigeria |
| 13 | The UK | Brazil |
| 14 | Indonesia | Norway |
| 15 | Iran | Kazakhstan |
| Prod | 88% | 77% |