| from natural gas | 13 | other |
| from petroleum | 5 | other |
| from these two fossil fuels | 3 | location |
| propane → be → extracted | 11 |
| propane → be → derived | 8 |
| propane → be → refined | 4 |
| negative | neutral | positive |
| 0.229 | 0.705 | 0.066 |
| Raw frequency | 23 |
| Normalized frequency | 0.583 |
| Modifier score | 0.900 |
| Perplexity | 282.626 |