I'm not aware of any charts for that. What theploww is saying is accurate. The rate of improvement in each category is determined by a combination of WE, practice time, game minutes / starts and potential. So to purely look at things from a WE standpoint would not be accurate.
To give you an extreme example, you could have a guy with a WE of 25, high-high potential in all categories, start him every game and he might gain 70+ points in a year, compared to a guy with a WE of 75, low potential in every category, and comes off the bench for 5 minutes per game who might gain a total of 10 points on the year.
WIth that said, players with a WE of less than 15 will probably not improve much over their career, WE of 15- 25 will improve over their career but likely fall far short of reaching their full potential in 4 years. Players with a WE between 25-40 have a chance of reaching their full potential, but usually require a redshirt year and/or early starts (as a freshman or sophomore). Players with a WE of > 40 will often get to their max potential, with players in the 40-55 range probably reaching it just by the end of their senior year, while players with a WE > 75 might reach their full potential by their junior year. Again though, everything is a function of their initial potential and playing time.