How could you only know?! 
I did a quick count of all the random tables. I counted 151 tables. I was in kind of a hurry, so take it with a grain of salt and +/- 2 or so. Also, some are just “choose a random department” or so, so you might want to substract about 5 to 10 in total, if this isn’t a “real” table for you!
There are 29 tables that are taken more or less directly of other books. Most are character creation (Core Rules and Player’s Guide) and the star system generation of the Shackleton Expanse. NB: @Modiphius-Jim remembered this tiny little error and there’s now an official errata for it 
I try to not state the obvious, too often, but: You’re the best, Jim! 
Some of the 25 tables are from other books like the recent Lower Decks supplement. As an addition: Didn’t have the possibility to find out about the backmatter, yet, so maybe I’m off by another one or two tables. Maybe five-to-ten as the Lower Decks Campaign Setting features critter creation.
There are an additional 25 tables that I classified as “evolved”. These are tables that I have seen somewhere else but that have either been adapted from d6 to d20 and/or expanded. Examples are the tables for species/phenomenon creation taken from the Science Division Supplement. These were essentially (massively!) updated for the Captain’s Log book. Another example are the “evolved” mission generation tables. These take root in the three Division Supplements and are massively expanded (to span over a handful of tables) for Captain’s Log.
Well, and then there are 97 tables I considered to be “new”. Again, some (dunno, about ten at max) are some three or four “liners”, but the overall majority are 20-entry tables, with the occasional d40 and d60 tables. Again, not a fan of randomisation choices with these, but of these 97 tables, about 90 or so are flat out d20 tables.
At least two thirds are genuinely new. And I’d say no more than 20% is directly copied without modification (mostly character/system creation rules that just work fine as they are).
Definetly a trove for GMs.