I'm pretty sure it's not something that we can 'stat'. One either has a fault that is reported, or one doesn't. That is the only way we can gather historical data.
I also think it comes down to the difference in EU's expectations ??. I, for example am not bothered in the slightest that I've lost circa 25Meg through cross-talk since I first went 'live' on FTTC. Whereas others go livid if they lose 0.5Meg. Conversely (pun intended), one EU may put up with an extremely noisy landline, whilst another will report the slightest one-off noise event.
I do however, think that a lot of REIN events go un-reported through EU's moving to the greater bandwidth product ?? Even though the REIN will affect the circuit, it is nowhere near as noticeable on VDSL, than it is on ADSL.