You can gain max 14 "activity" in a 2 week-period( https://bitcointalk.org/index.php?topic=582736.0 ) and the amount of activity depends on the number of posts you have already made.

Ex. 1) you post in 2 activity periods, you have 20 total posts. You have 20 activity in total
      2) You post in 2 activity periods, you have 28 posts. You have 28 activity in total
      3) You post in 2 activity periods, you have 35 posts. You have 28 activity in total