References:
- https://spacial.com/interesting-facts-about-radio-broadcasting/
- http://www.radiomatters.org/index.php/2018/09/10/5-facts-and-radio/
- https://newsgeneration.com/broadcast-resources/radio-facts-and-figures/
- https://mediatracks.com/resources/radio-facts/
- https://www.marketplace.org/2014/05/29/more-fun-facts-about-history-public-radio/