17.4% of CPAN uploads have no license in the META files
I just checked the 1000 most recent CPAN uploads and 174 of them did not have a license.That's 17.4%.
According to the history of the metayml_has_license metric of CPANTS, there has been a constant improvement since 2003, but I feel it is still too high.
Especially if you take in account how easy it is to add license to the META files.
What about making a New Year's resolution to add the license key to each one of your modules?