The boygrup GreatGuys debuted in 2018 and only released 17 songs so far wich are 3.4 songs a year on average
So, is ther either an artist who debuted in 2018 and has less songs (need to be someone who is still active!) or they exist for longer but have made on average less than 3.4 songs a year?
Blackpink has released 25 songs to date and the group has existed since August 2016 (not including solo songs). So they've released an average of 4.1 songs per year.
If you include solo songs, it would be 30 songs, an average of 5 songs per year.