OK; so around half of people (households) in the UK receive TV over the air. Gotcha.
I'll only add that this is surprising to me; I would have thought that the country (countries) would be as well-wired as the US is. There must be reasons ...
The reason is there was little interest in cable until the 80s. However, satellites were going up at around the same time, and putting up a small dish antenna was cheaper than wiring each home. It took a while, and some bankruptcies, but eventual Sky's satellite service developed a fairly big market, and cable never got that big. They only wired up the denser neighbourhoods, where the cost per home was lower.
Currently we can get the main TV channels from terrestrial broadcast, satellite broadcast, cable or internet. I don't think there are figures for how many people currently use each option, but a lot of people still use the terrestrial broadcasts. The TV licence is unrelated to the medium you use. If you watch live TV through any medium, even watching only foreign TV channels over satellites or the internet, you need a TV licence.
Especially for young people, live TV is not part of their day, even for immediate things like news or sports. The BBC and ITV channels used to provide a lot of good stuff to watch, but they are now largely irrelevant, and the viewing figures for the most popular shows are way below those from the heyday of broadcast TV. So, the number of licences is falling. I think its dropping at about 500k per annum.