Figure. The cumulative frequency distribution of persons according to their mean CAL in millimeters (mm) over 2 yrs. Results are given according to the presence of JP2 and non-JP2 types of A. actinomycetemcomitans (Aa) at baseline. Two individuals were positive for both JP2 and non-JP2 types of A. actinomycetemcomitans, and these were included in the group positive for the JP2 type only.