>>58856599e621 has both porn and safe art, if you filter out the porn by adding -rating:e as an extra search parameter you get the list of non-nsfw art of whatever you're searching. If you count the number of non-porn posts by multiplying the number of rows and columns on the first page, then multiply that result by the number of pages, and for a tiny bit of extra accuracy subtract the number of posts missing on the last page, you get an accurate approximation for the number of non-porn artwork of that Pokemon, now if you subtract the number of safe-rated posts from the total number of posts you get the ACTUAL amount of porn. Which for Umbreon is: 22414 (total) - 6974 (safe) = 15440 porn posts, now if you do that with every other Eeveelution you can figure out the real number of porn drawings of each one and make a real comparison.
The total amount of porn on e621 of each Eeveelution is:
Umbreon: 15440 (22414 total posts, 6974 non-nsfw)
Eevee: 12952 (21427 total, 8475 safe)
Sylveon: 12303 (18543 total, 6240 safe)
Vaporeon: 10896 (16967 total, 6071 safe)
Glaceon: 9078 (14550 total, 5472 safe)
Espeon: 6537 (10509 total, 3972 safe)
Jolteon: 6053 (8401 total, 2348 safe)
Leafeon: 5443 (8742 total, 3299 safe)
Flareon: 4858 (8004 total, 3146 safe)
sources: e621
thank you for reading my research paper on pokeporn