Table 5
Areas of study.
| Type of area | Total | Period % | |||
| Articles | % | 1964-1999 | 2000-2014 | 2015-2020 | |
| Environmental | 93 | 41.5 | 0.0 | 46.6 | 36.4 |
| Social | 72 | 32.1 | 66.7 | 27.2 | 37.3 |
| Economic | 38 | 17.0 | 0.0 | 16.5 | 16.9 |
| Combination of areas | 21 | 9.4 | 33.3 | 9.7 | 9.3 |
| Total | 224 | 100 | 100 | 100 | 100 |
