relative reference for mildew

We rarely see mildew here but now it is on things that rarely or never have had it before. Can someone give me a relative rating scale. How big a problem is it on the following common old roses? Dr. Huey, Garden Party, Frau Karl Druschki? Are they average mildewers, more resistant or more susceptible than most. I’m trying to estimate the problems on some of my seedlings.

Dr. Huey is very bad.

GP and FKD are both average here but susceptible.

DH and FKD mildew here. GP blackspots like mad here.

In my part of the world DH generally drops its leaves from BS before the PM can get seriously established.