How often to bluff?

[Moonsugar]

Ok, so I am a tight player and my raises and reraises get good respect. Since this is true how do I figure out how much I should bluff?

Let's say bb=100, 8 players left tight UTG limps in and folded to me on button, we both have 1300 chips and no huge or really short stacks in the blinds. If I raise here x%, what percentage of x should I be bluffing? Isn't there some game theory bs that tells me how to figure this out?

Reason I ask is that I have started bluffing more and it has worked out very well. Need to look for theory as to what frequency I should bluff.