Just went on a time journey on Spotify, from about 2003 to 2013. I have narrowed down my last year of being in the pop music loop, and it looks to be 2010, the year I turned 27.
I think the decline started even earlier, around 2000-2002, because even if I was all right with the pop music of the time, it had started moving in a direction I didn't outright love.
They say you stop being with it as you get close to 30, so 2010 as my last year of enjoying chart music sounds about right to me.