How to use chart "tests runs by requirement"

Hello,
I want to use the dashboard chart "tests runs by requirement" to know the number of requirement coverd by release. Also, several requirement are link with tests, and for each release, tests are selected in test sets and this tests sets are linked with release in progress. But if I don't link all my requirement with the release, when I filter on the release in progress, the chart is empty. So if for each release, I must link each requirement with the new release, is very spent time, and so this chart is unusable.
Someone have an idea for obtains for each release the percentage of requirement covered, whithout link each requirement with each release ?
Thanks