For a really certain answer, you'd need to look at the contract. 16% is a sort of unusual rate (at least for the fields I work in) - it's a little high to be a % of list, but quite low to be a % of net.
Are you working with an agent? One of their useful features is their familiarity with publishing terms (and scams), so they can explain the individual terms of your contract to you.
If you're working on your own, you REALLY need to read the contract, and to ask for clarification on exactly what's meant if the royalties are paid on net. (this might just be the deduction of the bookseller's discount, but it could also include printing costs, etc.) Some of the writers' associations have model contracts online for your to compare yours to. I like the one at EPIC for e-book contracts, and I know the SFWA has some up for their genre, as well, although I've never used that one.
Sorry it's not a more concrete answer, but I don't want to steer you wrong.