via danny_boy in: http://originaltrilogy.com/forum/topic.cfm/Theory-on-the-1997-restoration/post/549347/#TopicPost549347

Talking about the SW SE from a Wall Street Journal article:

Eventually 748 of the 2,228 shots in the movie were redone in the course of creating a new negative

33.57% Which means were missing quite a few. (my count is a little higher then zombie's spreadsheet but is shot specific and i'm at 251 visual, don't know if the 748 number also includes audio changes) [and i'm missing two shots somewhere... my count is currently 2,226 for original 77 SW]

But in the same article they talk about:

Other pieces weren't even original negative, but intentionally degraded duplicates that Mr. Lucas had stuck in to avoid emphasizing the quality of adjacent optical effects, some of which were so crude as to be almost unacceptable.

So that could mean anywhere there is a shot similar to a SFX shot, the shot before and after could be up for SE Change consideration. [I can open up a copy of the spreadsheet if anyone wants to go thru and make a guestimate.]