Easiest way to achieve this is the following.
After selecting the graph go to “Display” → “Modify display options” → “Graph time range”
Here you select a define range or insert your own dates.
Now you have the “Minimum” and “Maximum” value of your graph and the difference is the amount of printed pages.
The number is not really a rounded value. It makes no difference if it is 79571 or 79579 pages as shown in your example.