Period distributions for periodic disk-bearing stars with P ≤ 20 days (top) and periodic non-disk-bearing stars with P ≤ 20 days (bottom) for both linear and logarithm distributions. The median value for P ≥ 2 days stars is shown as dotted line. There were 80 disk-bearing stars and 799 non-disk-bearing stars with P ≥ 2 days and P< 20 days. The red bins show the fast rotators with P< 2 days excluded from the analysis.