Size of phoneme inventory

Phoneme inventory
wals.info/feature/1A - Consonants
wals.info/feature/2A - Vowels

Vowel

Vowel
Front Central Back
Close i u
Mid ə
Open ɐ̞

Consonant

http://phoible.org/parameters - on top right filter "combined class" = "c". The nasals might be too ambiguous because they are also created through assimilation, e.g. /ng/ = [ŋg]. /ʔ/ is commonly not written. That leaves ʃ (862/2155 (40%)), ʒ (310/2155 (14%)). These are assigned the two lowest letters in ILA: C = /ʃ/ and Q = /ʒ/.

The resulting set has as the least frequent values the /x/ (392/2155 (18%)) and Q = /ʒ/ (310/2155 (14%)).