It isn't clear what percentage of them work in jobs that involve interaction with the public / businesses (and are therefore bribeable), but I would guess 50%, not 2%.
There are quite a few other factors to this calculation, though.
Quite often, bribe receivers pay a portion to their managers (who aren't directly bribeable but make hiring and promotion decisions). This happens in property registration offices for instance.
Also, not everyone bribeable actually takes bribes. There's a significant number that don't. For instance many postal workers and doctors don't take bribes.
Finally, bribes are very unequally distributed. A minister might get paid $100m, and bribes would basically form 100% of their income.