Decided by a jury of 500-ish musicians and whatnot, via the American Film Institute.

1. Star Wars - 1977 - John Williams
2. Gone With The Wind - 1939 - Max Steiner
3. Lawrence of Arabia - 1962 - Maurice Jarre
4. Psycho - 1960 - Bernard Herrmann
5. The Godfather - 1962 - Nino Rota
6. Jaws - 1975 - John Williams
7. Laura - 1944 - David Raskin
8. The Magnificent Seven - 1960 - Elmer Bernstein
9. Chinatown - 1974 - Jerry Goldsmith
10. High Noon - 1952 - Dimitri Tiomkin
11. The Adventures of Robin Hood - 1938 - Erich Wolfgang Korngold
12. Vertigo - 1958 - Bernard Herrmann
13. King Kong - 1933 - Max Steiner
14. E.T. - 1982 - John Williams
15. Out of Africa - 1985 - John Barry
16. Sunset Boulevard - 1950 - Franz Waxman
17. To Kill a Mockingbird - 1962 - Elmer Bernstein
18. Planet of the Apes - 1968 - Jerry Goldsmith
19. A Streetcar Named Desire - 1951 - Alex North
20. The Pink Panther - 1964 - Henry Mancini
21. Ben-Hur - 1959 - Miklos Rozsa
22. On the Waterfront - 1954 - Leonard Bernstein
23. The Mission - 1986 - Ennio Morricone
24. On Golden Pond - 1981 - David Grusin
25. How the West Was Won - 1962 - Alfred Newman

My question is: are there so few recent scores on this list due to a mathematical reason (more movies produced prior to 1980 than after), a quality reason (older scores simply better, on the whole), or an aging reason (a score needs to “age” before its impact can be accurately judged).  No answers here.