Now, here's the UPSID data turned into grafx
There's some observation that can be seen here:
Phoible merges true-mid with upper-mid vowel *except* the central ones where it merged down instead. The lax high central vowel seems to be merged up with the tense high central vowels (It doesn't make any much difference).
The raised low vowels seems to be merged down with the true low vowel.