Would be nice to have not just the current period but also the ability to browse through previous ones. Along with the idea... some design considerations/suggestions.
1) Consider the data local stored (responsibility of the storage node user).
2) Consider the data stored elsewhere (if the node is destroyed, the data can still be recovered). This can be done via an alternate path (configured under config.yaml), NFS share, etc.
3) Ability to restore/backup the above to a specific node.
4) Progress/compare mode (add comparison details against the last period).