Triterm histogram



20 +
   | X 
   | X
   |      --- 
   | X     |
15 + X     |
   | X     |
   | XX   ===
   | XX    |
   | X     |
10 +       |
   |      ---
   |
   | X
   | X
 5 + 


m=13 (65%)
s=3.9