I've never gotten a raise less than a typical cost of living raise, which is around 3 or 4%. I think it's only fair of a company, if they typically do give out raises, to let employees know if there won't be any raises a given year because that's money people sometimes rely on. I am not sure if would make me want to leave for a new job but it would depend on the situation, how much I loved the job, how long I'd been there, etc.
A larger raise is great because it's obviously more money but to me it means I'm doing a great job. And it shows they're willing to give big raises when people do a good job.
I think an average raise should be at least 3%...which is basically a cost of living raise. At my company, 5% is pretty normal, 6% means you're doing really great, and anything over is above and beyond great. Largest raise I've received is 30% but that's also because they wanted to keep me and knew other companies were interested.