It would have been less confusing to have vertical lines rather than an x axis however they wanted it to look like a soundwave. However even though I am an electronic musician who works with soundwaves I didn't notice the metaphor until reading the comment here.

Thanks for pointing that out. It is a bit like the distribution on a violin plot then. But it still is weird how the colors are distributed and albeit I think it does indeed look nice, I think this plot shouldn't be in this community...

I don't know how to but this more clearly. The distance between the top and the bottom of the coloured strip at any given year; the thickness; represents the annual revenue.

This is actually a pretty common format for representing the evolution of parts in a total, because you can clearly see the share, the combined revenue and the total revenue over the years (that's the area). It is just that this one has been made symmetrical because it is easier to follow and just more pretty.