This provides an interesting (to me, anyway) analysis of executive orders issued by various Presidents. It's dry reading. It's from George Mason University's Mercatus Center - it appears to be a credible source, from what I can tell.
Of course, it doesn't list all of those orders and what they actually did, so that people can determine which ones they think are valid, which are bullshit, and so on.
Neither does it take into account the makeup of Congress - one would expect a President to issue more executive orders when Congress contains a higher proportion of the opposing party, I would think. Or at least more which actually influence policy.