Coffee, Black

When you order a coffee in public these days,
Your order comes to you in various ways:
The cups could be styrofoam, china or glass,
(In a french restaurant it comes 'dans une tasse'),
But wherever you go, you get, so it seems,
A plastic container of "10\% Cream".

Now, I think it's good that they label the stuff,
But the label itself doesn't go far enough.
It's ten per cent cream, but I won't be content
'till I know: what's the other ninety per cent?