In our analyses, only 12 out of 499 items were maximally informative at any ability level. These are the items that will be selected when Fisher information is optimized during item selection. It is obvious that their exposure rates will be high. The same phenomenon can be observed for the group of items that are 2nd most informative or 3rd most informative. Since only 26 items had to be selected for CAT, it demonstrates why only 20 percent of the items in the bank are actually administered.