ABV% increase range info...

I did search but was unable to locate the info.,,

My question is: On average how much more ABV will be added during secondary and bottle conditioning?

I realize no 2 beers are the same; style, temps, yeast strains and the like all play a factor. I am looking for a rough or mean % number range. FYI I am only transferring the beer to secondary, I am adding nothing to it.

Is .2-.5% pretty close?

Your beer should be done fermenting before moving it into a secondary vessel (unless you're adding something to it to do a true secondary fermentation) so there should be no additional alcohol created at that stage. And when you add the typical 4-5 oz of corn sugar to a 5 gallon batch you should typically see about a 0.25% to 0.3% boost in ABV, so your guess was pretty close.