Study the data tables below which show the changing population structure of Northern Ireland.
| Age (years) | Number of people |
|---|---|
| 0-19 | 450,000 |
| 20-39 | 490,000 |
| 40-59 | 410,000 |
| 60-79 | 270,000 |
| 80+ | 60,000 |
| Age (years) | Number of people |
|---|---|
| 0-19 | 460,000 |
| 20-39 | 450,000 |
| 40-59 | 520,000 |
| 60-79 | 360,000 |
| 80+ | 90,000 |
Which age group experienced a decrease in the number of people between 2001 and 2021?