It really depends on what you call "long distance". Anyway, transportation loss for entsoe is public data [1]. You'd need to cross it with production/consumption data [2] in order to get relative numbers.

For instance, France consumed 442 TWh and reported 1.07TWh of losses in 2022, which would be about 2.5% transportation losses.

[1]: https://eepublicdownloads.blob.core.windows.net/public-cdn-c... [2]: https://eepublicdownloads.blob.core.windows.net/public-cdn-c...