Marc G. Fournier posted some statistics gathered from his BSDStats service. It’s possible to activate this right now on DragonFly. Just put
monthly_statistics_enable="YES"
in /etc/rc.conf. For details, there’s the man page.
A running description of activity related to DragonFly BSD.
It needs to be put in /etc/periodic.conf
Are you sure? It’s running on my system (I recall seeing the output in the monthly reports) and I don’t have a periodic.conf.
I just checked, it just works because this specific script as the only periodic script checks rc.conf too.
But it is part of the /etc/periodic/monthly, and the options are described in periodic.conf(5).