Distribution
       +             +            +            +            +             +
  90 +++-------------+------------+------------+------------+-------------+++
      |                                                                    |
  80 ++                                                                  **++
      |                                                                  **|
  70 ++                                                                  **++
  60 ++                                                                  **++
      |                                                                  **|
  50 ++                                                                  **++
      |                                                                  **|
  40 ++                                                                  **++
      |                                                                  **|
  30 ++                                                                  **++
  20 ++                                                                  **++
      |                                                                  **|
  10 ++                                                                  **++
      |                                                              ******|
   0 +++-------------+------------+**--------**+--***-------+**--**********++
       +             +            +            +            +             +
       0             10           20           30           40            50
                                     SEQ_LEN