09年出来的数据：

1. Massachusetts Institute of Technology2. Stanford University3. Carnegie Mellon University4. University of California-Berkeley5. Cornell University6. University of Texas-Austin7. University of Illinois-Urbana-Champaign8. Princeton University9. California Institute of Technology10. University of Washington11. University of Wisconsin-Madison12. Harvard University13. Brown University14. Yale University15. University of California- Los Angeles16. University of Maryland – College Park17. Rice University18. University of Michigan-Ann Arbor19. University of Southern California20. Columbia University