Rating Inconsistencies on "Through the Wormhole"

I recently noticed a discrepancy with the ratings on the show "Through the Wormhole." The overall show rating is listed as 8.6, but after going through all the episodes, none of them have a rating higher than 8.3. This seems like a potential issue with how the aggregate ratings are being calculated or displayed. Has anyone else noticed this issue? Is it something that can be fixed on the backend, or are the individual episode ratings not being properly factored into the overall show score?