Not figures.
PSMA PET scans were already available privately in the UK before 2018 when I was diagnosed - all sizable private centres had the capability. They've cost about £2,500 privately since 2018 (so in real terms, they've got cheaper).
The Paul Strictland Scanner Centre (co-located with Mount Vernon Cancer Centre in the UK) started offering PSMA PET scans on the NHS by the end of 2018 (which I've heard was the first to do so), and this became more standard there on the NHS in 2019. I suspect that by the end of 2019, all the major NHS cancer centres were offering them. One of my support groups had a talk in 2019 where MVCC said they'd switched from Technetium 99m bone scans over to PSMA PET scans, having found them much more accurate. (However, MVCC are mainly a tertiary care centre - most of their patients have already had their scans and been diagnosed before referral there for treatment, they don't directly diagnose many of their patients themselves.) They were only still doing Technetium 99m bone scans in the case of patients on trials where this was part of the trial protocol.
Increasingly, I am seeing PSMA PET scanning available at the larger district general hospitals now too so things are improving, but many still don't have the capability. In theory, those can refer patients elsewhere for scans, but that's much less likely to happen. I was talking about this with a oncology radiologist who does PET scanning. They said the hospitals without the capability on site just don't have oncologists who are familiar with PET scans for diagnostics. They see patients who pay for a private PSMA PET scan elsewhere, take the report back to their NHS oncologist, who then doesn't really know what to do with it. So if you are at a cancer stage where these scans are particularly important (such as recurrence, or a particularly risky/tricky initial diagnosis), you probably do better to be referred to a hospital which has its own PSMA PET scanning (and SABR) service, where you are more likely to get the appropriate diagnosis and treatments.
The US was notably late in adopting and rolling out PSMA PET scans. They didn't get FDA approval until 2020.