Biggest idol group songs from 2016 to 2021 (so far) in Korea

Quote from Spsnowflakes

Oh yeah, maybe if we are talking abt "Best performing song in year 2019/2020/2021 etc" then yeah, thats probs how it work. I just don't think thats whats OP is talking abt Ig.

I’m talking about the biggest song released that year which take overall.

Spring day wasn’t the biggest idol group song in 2017 but through the years it outsold all the competition reason why is consider as the biggest idol group song that year.

Rollin was released in 2017 but it got big in 2021 that’s why I added it as the biggest idol group this year so far.