First, sry for my bad english 
Since a few days I am a little bit confused about my stats.
Three days ago, my rank was 10 or 9 and the next day 21.
Yesterday around 10pm my rank was 19 and today i start with 24.
Also the Number of “total Aircraft” drops. Yesterday ~138.000 and this morning 130.000.
In recent days, the number of my data increases but my rank drops 
flightaware.com/adsb/stats/user/nevrmind
Can someone enlighten me please.
All of the ranked stats pages represent a running history of the last 30 days. At the top of the page it says “Statistics are updated every 15 minutes and represent activity for the last 30 days.”
If you have been around more than 30 days then your older data will be excluded from the total once it becomes old enough.
Affected by Lufthansa strike?
also check to see if anyone is another country above you there busy time could be your quiet time. Also like people have mentioned its a moving number over 30 days.