Looking to Join HVAC-R, Plumbing or Electrician in Calgary as Apprentice

Hello anyone in Construction Trades in Calgary specifically HVAC, Plumbing or Electrician? Im looking to join the apprenticeship but im unsure which one is more In-Demand right now (i called the local union for Plumbing but they are unresponsive). Any other trades suggestions that are in demand are welcome.

Im completely have no trade experience but is eager to learn a skill, that i can benefit by learning.