feeder statistics


can anybody explain how does feeder statistics work?
Since 2 days ,at 00:00 i save a screnshot of feeder statistic and when i control again i find a different registration in less:
for example: at 00:02- 5th of September ,i saved a screenshot with 3709 aircrafts seen,now at 11: 42 local time they are
Thanking for help,best reception to everybody