100% sales. Radio is irrelevant because its at the mercy of program directors. Paid streaming is irrelevant because people already paid their monthly fees, so they don't give a **** if they fail to hit the skip button while they're busy checking their email. And YouTube streams are irrelevant because no coins are exchanged.
imo sales & streaming are what truly represents a song's popularity with the public so they should have the highest weight. Airplay should still count since radio tends to play what's popular anyways. However, airplay is much easier for labels and corporations to manipulate so it shouldn't count as much as sales and streaming.
Streaming should only count from Youtube if it's from the artist's official channels, not some random viral video that happens to use the song.
its great now, so many people putting so much emphasis on sales sales are dying. streaming is obviously>>>> jump on it now because in a few years digital sales are going to look like album sales, dead!