(Lack of) Radio Advertisements

I have been trying to research radio advertisements in the last few weeks to give me a few ideas for my own project. In this time i have descovered that a newspaper radio advert is very uncommon. Even the tv ads aren't in their bucket fulls either. But there are plently more tv ads than radio ads. I have no idea why this is. Not even local papers seem to advertise on the radio, weather it be through a lack of funding or weather it being just unneeded.