Autocalculate the issue done ratio only for certain issue statuses
Though we need to use the % done field in Redmine, there is no reason not to have it work automatically for certain statuses. For example a "New" issue could be set automatically to 0% and a "Resolved" issue could be set to 100% done. The user could always change pertentages if needed...
Moreover, that would be an excellent way of avoiding 0%-closed issues.