The snowfall from the Feb 10, 2018 snowstorm covered most of IA, northern IL, northern IN, and southern MI. While some locations in that snow swath saw over a foot of snow, let’s assume the average depth of the snow over this area was 9 inches. If the total area covered by the 9 inch average depth was 72,300 square miles, what percentage of the volume of the Grand Canyon would this amount of snow fill?