OK, those are production leaks, not transport leaks. I don't know how high production leaks are here in Europe but I assume them to be lower due to stringent rules. There is also quite a bit of natural methane leakage from swamps, wetlands and other similar sources as well as from agriculture. ESA has a satellite which can measure this [1], it shows methane leakage from landfills can also be quite large [2].
All those leaks contribute to the externalities of natural gas. I don't know the relative contributions between extraction and distribution, but leaks in the distribution network are also a problem in Europe [1]. It's certainly true that extraction leaks can be so substantial as to make shale gas worse than coal [2] (twice worse over 20 years!).
Landfills (and agriculture) are big sources of methane. I think this is a pretty good start to figure out what the EU is doing to reduce all sources [3].
[1] https://www.esa.int/Applications/Observing_the_Earth/Coperni...
[2] https://www.esa.int/Applications/Observing_the_Earth/Satelli...