Subject | Natural gas used (billion m3) | Calorific value (billion MJ) | Average | |
Year |
| min. 32 MJ/m3 | max. 42 MJ/m3 | 37 MJ/m3 |
1935 | 0.071 | 2272 | 2982 | 2627 |
1958 | 0.400 | 12,800 | 16,800 | 14,800 |
1980 | 1.531 | 48,992 | 64,302 | 56,647 |
2013 | 3479 | 111,328 | 146,118 | 128,723 |