You can always create a report based on the tblcplogoninfo database table to only report on logons that occurred in the last X number of days. Alternatively, you can adjust the "Delete logon information after X days" setting under Configuration\Scanning Setup\Server Options so logon events are deleted more quickly.
We have added your request to display the information in the Summary tab to our customer wish list, but do not have a release date for it.