A bit depends on your paygrade, but as near as I can tell from BUPERS and a quick glance at the CREO list… well, I’ll just copy-paste part of it here
Rating E1-E4 E5 E6
CTI(A) – 1 1 2
CTI(P) – 1 1 1
CTI( C) – 1 2 3
CTI (K) – 1 2 3
CTI (S) – 1 2 2
CTI ( R) – 1 2 2
CTM .. – 1 1 3
CTN . – 1 2 2
CTR . – 1 1 2
CTT .. – 1 2 2
IT . . . – 2 3 3
Okay, the columns don’t line up, but 1 means undermanned, 2 means about right, and 3 means overmanned. IT is pretty top-heavy and don’t need any more 2nd or 1st classes. CTs are a little hit-or-miss, but it appears that CTO already merged with IT and CTM is going to be split between ET and IT soon, so you may wind up as an IT again anyways :D