Why revenues almost always zero?

Date,Country code,Country tier,adrequests,available,offers,started,views,revenue
"2017-01-09 00:00:00","AE",3,0,0,0,3,1,"0.00"
"2017-01-09 00:00:00","AR",5,46,46,0,5,5,"0.00"
"2017-01-09 00:00:00","AU",2,0,0,0,5,0,"0.00"
"2017-01-09 00:00:00","AZ",6,0,0,0,1,0,"0.00"
"2017-01-09 00:00:00","BG",4,0,0,0,6,0,"0.00"
"2017-01-09 00:00:00","BR",5,23,23,0,26,10,"0.00"
"2017-01-09 00:00:00","BS",5,0,0,0,1,1,"0.00"
"2017-01-09...