why the resource super profits tax is fair, page-18

Any ideas - what is the actual contribution that the mining companies bring to the country budget? Not the employees, but the companies only, as a %.

I overheard something on a radio program, about 1/2 year ago, but my attention was elsewhere:

The topic was - why do we talk about China 'saving us' all the time, when the contribution from mining companies is miserable - below 3%.
They were also saying that the way it is all structured, the contribution can't go above 5%, but that is only theoretical, it never gets there, and it's 2-3% really.

As I said my attention was elsewhere, so I'm curious?