get
https://try.count.ly/o?method=retention&api_key=&app_id=
Get retention data (available in retention plugin)
Retrieves user retention data.
- _id - represents the date of data in "yyyymmdd" format
- tu - total new users joined in that date
- 1 - how many of joined users left on date +1 day
- 2 - how many of joined users left on date +2 days
- etc