Topic
- Armed Forces 26
- Commerce 26
- Emigration and immigration 26
- Recycling 25
- Refugees 25
- Precipitation (Meteorology) 24
- Watersheds 24
- International regimes 23
- Migration 23
- Water reuse 23
- Census 22
- Dams 22
- Education 22
- Palestinian Arabs 22
- Fertility 21
- Resource allocation 21
- Economic development 18
- Religion 18
- Sewage 18
- Building 15
