If we're talking about pinks, then I find I lose quite a few fish as they do have soft mouths - it can be a fine line between playing the fish out too long vs. ripping the hook out of the mouth. 50% is a respectable land/loss ratio for chrome bright pinks IMHO.
As for coho - I'm shooting about 75% landing success which I'm happy with so far. I find that if you hook a coho - they're actually pretty easy to bring in until they feel the gravel and go "nuts" and roll and jump. This is when it can get a bit crazy! I find that if I can keep a constant pressure on the fish, and keep the rod tip up, chances are I'll land it. I also agree that sharp quality hooks are key.
As for springs - I'm more like 25% landing success because I'm using light gear and usually just break off. As for spring jacks - I haven't lost one yet. I haven't caught a ton of them - around a dozen or so...