2015 looks like the number of RMs will be in the 78 range. So, a farily consistent number the past few years.
As for how many starters have been RMs, I can help you with that, but I'd first need to know which 22 you'd like to count as starters (opening day starters, bowl game starters, would-be opening day starters if not for injury, etc.). If you have the names, I can tell you the numbers.