The following pre-defined reports are provided in the report editor for Code Review. They can be dropped onto the 'Drop report type here' field to automatically generate a report with the entity, series and/or x-axis configured.

Actions by date: Creates a graph that shows all actions grouped by date
Actions by responsible sum by state: Creates a graph that shows all actions grouped by who is responsible
Comments by date sum by from: Creates a graph that shows all comments by date grouped by who originally added the comment
Commits by committer: Creates a graph that shows all revisions grouped by the committer
Commits by date sum by type: Creates a graph that shows all revisions grouped by the date and by type (either pre-checkin or post-checkin)
Reviews by committer: Creates a graph that shows all reviews grouped by the committer of the code review
Reviews by date sum by state: Creates a graph that shows all reviews grouped by their current state (for example, approved, rejected or pending)