Potentially every 23 hours Mappers are transfered to new players if the corresponding majority changed. This is about the largest such transfers in the history of Badge(r)s. There is also a page about latest such transfers (together with rulers).
Link: Largest Mapper Transfers
This is a statistics from the meta group. There are many more Statistics. Stay up to date with (most) of Badge(r)s statistics via the Significant Statistics Changes page.