Those are the average abundances in the iron that forms the asteroid metallic cores, which are exposed in a few asteroids, presumably because of ancient collisions.

The asteroids where such cores are exposed, instead of being buried under huge amounts of rocks, like in the planets, are those that are targeted for mining.

The iron meteorites are pieces detached from such asteroid cores, so they provide samples of their composition.

Some meteorites, the so-called chondrites, come from small bodies that have never aggregated into bigger asteroids or planets since the formation of the Solar System, so they have a chemical composition close to the average composition of the Solar System.

Other meteorites have been detached from big bodies, like asteroids, planets (e.g. from Mars) or from the Moon.

These meteorites are either made of rocks, when they have been detached from the surface of such bodies, or made of an alloy of iron, nickel, cobalt, germanium, some times also silicon, together with other metals that are present in much smaller quantities, when they have been detached from exposed asteroid cores.