Sorry to take so long in posting.
The "Trains" (Kalmbach Publishing) Locomotive annual for 2020 came out last month, and has some numbers.
----One "article" -- more of a tabulation of locomotive headlines -- gives the production totals for GE and EMD for every year from 2000 to 2019: GE outsold EMD in every year. (2002 was a photofinish, with GE about 1% ahead; other years saw GE ahead by much larger margins, GE often building 2 or 3 times as many units as EMD, and over 5 times as many in 2009.) I won't, unless someone really twists my arm, try to copy out all these numbers: the ratio fluctuates, and the numbers include export as well as domestic units, and in the past few years rebuilds as well as new: all making it very hard to discern any kind of trend.
----There is also a "census" of the locomotive fleets of the big six North American freight railroads (BNSF, CN, CP, CSX, NS, and UP). In 2020 the combined fleet was 51% GE to 46% EMD (the rest being from minor builders like NREC and Railpower, etc, and a few preserved but active steam locomotives). As to n01jd1's observations, CSX's fleet was 54% GE to 41% EMD.
----They also (along with some reprinted articles from past years: I wasn't impressed by Kalmbach's willingness to pay for new content) give the census figures for 2000: the overall totals had 36% GE to 66% EMD (with CSX -- the heir of GE-friendly Seaboard System and EMD heavy Chess -- at 40% GE and 55% EMD.
----The comparison shows a dramatic increaser in the proportion of GE locomotives. From the standpoint of the l train watcher, the change is perhaps even more dramatic, since mainline freights are likely to be headed by the newest and most powerful units, which are now predominantly GE. (In, say, the 1970s, there would have been a similar GE bias, though then it made GE look like a larger minority than it really was instead of exaggerating its majority: then as now, GE locomotives tended to be newer and on average more powerful than EMD.)
I've been a railroad fan since my student days (bought my first issue of "Trains" in 1970), and am something of a "fan" of GE locomotives. (Not sure why: maybe it started out in part as "rooting for the underdog"!) I was always sad that there were, for example, so many more GP-30 and GP-35 than U25B. And, despite "my team's" triumph in the past two decades, when you look beyond the mainline freights... there are STILL a lot more GP-30 and GP-35 out there than there are U25B!