An international charity builds homes for disaster victims. Often the materials are donated. The charity recently built $45$ homes. $20\%$ used granite for the kitchen countertops, while the rest used porcelain tile. $15$ of the homes used red oak for the wooden kitchen floor, $20$ used white oak, and $10$ used maple. If a disaster victim is randomly assigned to a home, what is the probability (in percent) of getting an oak floor with granite countertops?