It takes a lot into consideration when there is/isn't a steal attempt. Pretty much I'll go into the game with a runner on first (with second base open) who has a speed rating of at least 40-plus. If that runner's steal rating is above about 50, there's a potential of him going if the situation is right (decent count to steal or hit-and-run, score range where a steal could happen, etc).
My RTTS catcher has a Prime Yadi arm by now and I do see a far amount of steals. Most of these steals come from players with 70-plus speed and 50-plus steal (and I do get some from a little less and they are easily "out by a country mile because their feet were stuck in the mud" -Matt V) When I come up with a 90-90 runner, I anticipate a steal at some point in the AB. If that runner is on and there's 0 or 1 out, if there isn't a steal attempt in the first AB, there's likely one in the next AB - especially if the batter is an RBI threat. So if I ventured a guess, I may see about 70-80 steal attempts over the course of a season (with about 140 GP) and after a quick search, that seems about the average for an elite-armed catcher.