You should visit a WebSDR site like this one http://websdr.ewi.utwente.nl:8901 http://websdr.ewi.utwente.nl:8901 as it nicely visualizes the bandwidth actually

You should visit a WebSDR site like this one http://websdr.ewi.utwente.nl:8901 http://websdr.ewi.utwente.nl:8901 as it nicely visualizes the bandwidth actually taken by a single broadcast, as well as how tightly neighboring signals can be packed. To answer your question, a broadcast of a certain kind will take the same amount of bandwidth regardless of the frequencies, but it's typical for the higher bands to simply offer more bandwidth and as such offer more broadcasting spots.