Suggestion for substantive change
I suggest the following revision with a minor adjustment to your improvement:
- The Berne Convention recommend that the duration of copyright be at least life plus 50 years. Countries may have shorter or longer durations.
- Most Berne Convention signatory countries have a copyright duration of life plus 50 years.
- Some countries have adopted longer durations: e.g., life plus 70 years for the United States of America and member states of the European Union.
- A few countries have a copyright duration shorter than 50 years.
I prefer not to introduce TRIPs / WTO into this conversation -- it complicates issues. The Berne Convention is more relevant here as the foundation for duration.
I also added the missing link to WP copyright duration.