Commercial tracks volume

Hi there I am a bit confused about this "issue". I'm having some kind of loudness issue. I don't mean making it louder and louder, still want to keep dynamics at 8 or higher. But how comes, that all the commercially released tracks are, if imported into reaper (mp3), measured at around +1.5db. If I measure my exported mp3 track, imported into reaper, it shows a value of about +0.3db. I mean how comes. I set my limiter always to -0.1 db, and it is not possible to make it any louder than that, but how comes, every commercially released track is about 1db louder if compared in reaper? Just to repeat, it's not about squashing dynimacs. But even good artist which keeps dynmics at around 10 or more, are having louder tracks than I do. It's always around 1db louder and I don't know how it comes. Thanks for your answers and for not starting a discussion about loudness war ;o))

a free plugin for measuring "inter sample peaks" along with some useful reading about the subject a common occurrence with mp3s, I usually master to .03 to reduce the problem, as does another more professional mastering engineer I worked with recently

I've a word of advice for the OP. Forget about all this loudness malarky altogether. Be part of the new paradigm. And set yourself free.Just make your mixes and to hell with the RMS levels.