The ten greatest American plays?

What are the ten greatest American plays? A recent survey of 177 theatre experts and students quoted by the Denver Post cites the following:

1. Death of a Salesman, Arthur Miller

2. Angels in America, Tony Kushner

3. A Streetcar Named Desire, Tennessee Williams

4. Long Day's Journey into Night, Eugene O'Neill

5. Who's Afraid of Virginia Woolf?, Edward Albee

6. Our Town, Thornton Wilder

7. The Glass Menagerie, Tennessee Williams

8. A Raisin in the Sun, Lorraine Hansberry

9. The Crucible, Arthur Miller

10. Fences, August Wilson

Not a bad list, huh, although anyone might quibble here and there. So what were the next ten, ranked 11-20?

11. August: Osage County, Tracy Letts

12. Glengarry Glen Ross, David Mamet

13. Buried Child, Sam Shepard

14. The Iceman Cometh, Eugene O'Neill

15. All My Sons, Arthur Miller

16. (tie) You Can't Take it With You, Kaufman and Hart

16. (tie) Joe Turner's Come and Gone, August Wilson

18. The Piano Lesson, August Wilson

19. Cat on a Hot Tin Roof, Tennessee Williams

20. American Buffalo, David Mamet

Some 265 plays were cited in the survey. You can read the whole list here.