| % Level of Required Maintenance | Total Production Cost =N=:k | Unit Cost of Production =N=:k |
| 0 | 117,716,000.00 | 97.46 |
| 10 | 122,977,000.00 | 101.82 |
| 20 | 128,218,000.00 | 106.16 |
| 30 | 133,468,000.00 | 110.51 |
| 40 | 138,711,000.00 | 114.85 |
| 50 | 143,976,000.00 | 119.21 |
| 60 | 149,242,000.00 | 123.57 |
| 70 | 154,486,000.00 | 127.91 |
| 80 | 159,727,000.00 | 132.25 |
| 90 | 164,979,000.00 | 136.59 |
| 100 | 170,251,000.00 | 140.96 |