It's nowhere near 12,000.
Here's a video that explains the figures, not that I expect you to watch it, much less admit just how wrong you are.
That video is 24 minutes long which would be difficult for people with an attention span that a goldfish would be ashamed of.
It is an interesting video though, for those who are interested. A good explanation of laws in the UK and US.
A quick explanation is that it's arrest for anything do do with the communications act, so that's any form of communication (post, telephone, television) and a small amount are via the internet... Beyond this only 12% lead to a conviction... of total charges, it's less than 10% for anything online.
I know a defence lawyer who deals with similar cases and you're not ever arrested for "making a tweet", you're arrested for things that would get arrested for doing things that would get you arrested if you did them face to face. Threatening, harassment, inciting violence does not magically become legal (and these are not legal in the US either) just because you did it online. "with a computer" is not a magic get out of jail free, if I were to beat someone to death with an IBM Model M keyboard it would still be considered murder (or at least manslaughter), just because I did it with a computer it inconsequential.
Now for the vast majority of cases she advises her client to apologise, that gets you out of a lot of trouble simply because it transfers the onus to prove your intent onto the CPS (Crown Prosecution Service) so unless you've got a strong history of harassment, threats, et al. and I mean a strong history, a very strong history.
If anything the US is currently proving that we (the UK) need to take more actions against people threaten, harass, intimidate and abuse others regardless of the method they use.