For which time intervals, is the percentage rise of population the same for the following data?
| Period | Population |
| 1970 | 40,000 |
| 1980 | 50,000 |
| 1990 | 60,000 |
| 2000 | 72,000 |
| 2010 | 80,000 |
1
1970 - 80 and 1980 - 90
2
1980 - 90 and 1990 - 2000
3
2000 - 2010 and 1990 - 2000
4
1980 - 90 and 2000 - 2010