Hi,
That does seem to be a bit heavy. Any idea how many hosts and VMs this vCenter is managing?
The first thing I would have your vCenter admin look at would be the settings for statistics collection. Large numbers of hosts/VM with stats collection turned up past the default settings could explain the high rate of change in your database.
EVERY task and event that occurs on vCenter or on any ESX host is logged in the database, so again, the more hosts that are involved, that higher the rate of change you could expect, just in general.