It's ok to have doubts!
I suppose CNN Philippines was the only one that shared a list of their favorite songs and albums of the year. And the same for other lists that are from one specific country. Or at least what they could find out. But If you are aware of more, you can share! So when they make the lists again next year, they might include even more infos from more sites.
Yeah when conducting "survey" or list I'm always interested on knowing the thought process on picking the sample since the results could wildly differentiate depends on the sample chosen.