Which Think Tanks Have the Greatest Impact on Public Policy?

Based on the latest statistics, here is the top 15 list:

1. Amnesty International
2. Brookings
3. Human Rights Watch
4. Transparency International
5. RAND Corporation
6. Council on Foreign Relations (CFR)
7. Chatham House
8. Cato Institute
9. Center for Strategic & International Studies (CSIS)
10. Peterson Institute for International Economics (PIIE)
11. International Crisis Group (ICG)
12. Bruegel
13. American Enterprise Institute (AEI)
14. Carnegie Endowment for International Peace (CEIP)
15. Stockholm International Peace Research Institute (SIPRI)