If it's only 5% they're bloody lucky, I'd say. I would have estimated it as more like 10%, with far more again being willing to pay a reasonable price and pirating when that's not an option.
The rise in legal useful services in the UK will almost certainly be a factor here, but as a film and music enthusiast who uses everything from Amazon through emusic to Bandcamp to get music and Netflix/Lovefilm through Film4OD/CurzonOnDemand for home viewing, I maintain the opinion that if I've checked half a dozen services and accounts to try and legally get at the product I'm seeking and the rightsholders have decided that I shouldn't be allowed paid access to it, then they lose nothing if I end up getting it elsewhere. (EG I'd happily pay up to £10 just for streaming access to Sky Atlantic, but Sky won't let me get that unless I switch to them as a provider - so they can sit and swivel, and those content creators who decided that giving Sky the exclusive rights to their contents get money from me only when they release their stuff on DVD. It's a net loss for all of us, but if they will insist on being bloody stupid there's only so much I can do....)
I happily pay for content, but I don't understand what sane individual would think that there's a difference between "Captain Underpants, in the UK, watches DL copy of eg current Big Bang Theory episodes, then buys boxset of that season 6 months later when it's released" and "Captain Underpants, in the UK, waits until that boxset is released 6 months after broadcast and buys it when it's released". They get the same money, at the same time, in both cases. If they want my money sooner, the way to do it is to give me DRM free access to paid-for episode downloads, at a reasonable price. The music industry eventually accepted this and, surprise surprise, is now reporting steady increases in digital music sales. I look forward to the day that the film and tv industry catch up.