Time to clear backlog is how long USCIS would need to decide every pending case if it kept deciding them at the same speed. It is not your wait: the pile includes cases on hold and cases USCIS cannot decide yet.
How to read the chart
The chart shows no time to clear the backlog for quarters in which USCIS decided fewer than 100, too few to divide by. USCIS does not publish a median processing time for this form.