For different look at "apparent bitterness" by beer style (relation of bitterness to potential alcohol), please see Jeff's chart on the subject.
Historic water chemistry also had an impact on the raw materials favored in that region. As discussed in the previous post, brewing water's residual alkalinity (RA) determines how dark wort can be effectively mashed. In general, the higher the RA of the water, which is largely determined by water hardness, the more the water can buffer against the acidic nature of darker malts. If the water's RA value is not high enough to handle the darker malts used in a recipe, then the mash pH plummets, which both reduces the grain's sugar yield and produces a thin and acidic wort. Cities like Dublin could handle darker malts, which required less malting control and skill, and they developed styles like stout. Conversely, cities like Pilsen have soft water that is free of most minerals and low in hardness. As such, Pilsen could not effectively work with such dark malts. They, in turn, preferred lighter malts and developed styles like pilsner.
In conclusion, water chemistry had a good deal to do with developing the beer styles we know today. It, along with available raw ingredients, shaped regional expectations of brewers and helped increase beer variety. Understanding these historical water profiles can help brewers make beer that is more authentic.