| Years | Population (million) | Per capita availability (m3) |
| 1951 | 34 | 5000 |
| 1961 | 46 | 3950 |
| 1971 | 65 | 2700 |
| 1981 | 84 | 2100 |
| 1991 | 115 | 1600 |
| 2000 | 148 | 1200 |
| 2013 | 178 | 1105 |
| 2015 | 190 | 1000 |
| 2025 | 267 | 659 |