Throttling Reporting Content Security Policy violations

https://sentry.io/settings/{organization}/projects/{project}/security-headers/csp/
makes mention that it is possible to have CSP violations only reported on a percentage of violations:

“We recommend setting this up to only run on a percentage of requests, as otherwise you may find that you’ve quickly exhausted your quota.”

But I can’t seem to figure out how this could be done. The browser itself uses the report-uri directive to determine where to send the report, but how I can I throttle these being fired off to Sentry? I cant seem to find any information anywhere on how this could be done.

Any help would be greatly appreciated!