The number you just clicked on is generated by our privately maintained hit comparison program. The program reads data from our hits file for the previous two months and the current month.
The monthly hit rate is computed by looking up the current hit count, subtracting the figure for the beginning of the second prior month, divided the result by the number of days so far in the current month and the prior two months, and, finally, multiplied by 30. This results in "normalizing" the computation to a standard monthly rate using a weighted daily average over the current and two previous months. The resulting number will tend to fluctuate less than from month to month. If you review it over a longer period, and average the numbers, it will provide a "ball-park" figure for how frequently the page of interest is being accessed.