according to Madonna's discography.

I think Madonna is an appropriate pop music barometer.

She attempts to cash in on the up coming styles of each decade:

the early to mid 80s output was phenomenal. Then there was a dip in the late 80s/early 90s. A bit of a comeabck in the mid 90s wiht William Orbit.

Then?:

Just shit shit shit.

We should learn from this