With the many plans for supporting a range of print volume (15 - 1500 pages/month), it would be nice to see your actual printing volume over a significant past period. In that way, you could determine if you have selected the appropriate plan for your needs.
When you look at the Instant Ink site, under Print History, you see information of the print volume per day for the selected month. For any completed month, the total pages printed is shown at the bottom of the page for Plan/Rollover/Additional pages.
I think it would be helpful to have a graph or bar display with the time axis by month, plotting the page count for each class (Plan/Rollover/Additional). You would then be able to make an informed decision on whether your selected plan is appropriate for your needs.