Almost every ICU source data file (resource bundle .txt file) includes a line with the CLDR data version:
While cheap in terms of storage (especially with pool bundles), this means that in a version upgrade thousands of files are changed even if there is no significantly new data. This is hard to review, especially on GitHub.
Let's please store the data version in only a few files, such as one per ICU, or one per "tree".
We actually have such a central file already: https://github.com/unicode-org/icu/blob/master/icu4c/source/data/misc/icuver.txt
It seems to be manually updated. Its CLDR version number should be written by the CLDR-to-ICU converter.
We could change any version-reading code to read that central version number, or fall back to it.
If needed, we could keep it looking for a file-specific version first.