Hi, please use black/dark colors next time when posting. Some of us have difficulty with that bright yellow you used.
Now to your questions;
CIC uses different teams of reviewers for each NOC. They are not subject matter experts but for administrative ease. Part of what they do is ensure that the responsibilities indicated by an applicant in their application matches the roles for each NOC as spelt out in the NOC list.
The NOCS you see' jumping high' are those occupations for which there are traditionally always high numbers of applicants. The other NOCS just happen to have less applications, there were even NOCS in past FSW programs which received no applications at all from applicants
Cheers