Thank you for your answers, however it is not completely clear.
According to GC help center, there is no way to go completely anonymous.
"... At this time, there is no way to block another geocacher from seeing your public profile page or your geocaching activity..."
On the other hand, when statistics are hidden, then the found and hidden numbers are shown anyway.
So why showing the question mark in the hidden top list, when this information is not hidden.