I would love an API call to fetch "Average time...

I would love an API call to fetch "Average time to first response" for my Helpdesk.

I guess it would take a time range (perhaps past 2 or 7 days...), thus it would be a moving average (that I can graph).

I want to feed this into my public website (or even a widget in my UserEcho page!), so that I can set Customer expectations as to our current average service time when they open a new Ticket.