Gaon is a ranking system made up of different music sites and distributing companies. The charts are calculated on the number’s that they have from Korean Online and Mobile Charts.
The Online Chart displays results from online music and album sales and streaming services while the Mobile Chart calculates the best selling ringtones and caller ringtones for each week.
“Hoot” soared to the number 1 spot on the 5th week of October.
Credits: http://fanwonder.com/?p=4626 , gaonchart.co.kr