why not just lie to them and tell them you make 20-30% more than you really do ?
Also the experience of being caught lying is emotionally and mentally draining for me so I stopped way way back. Like in childhood. I wouldn't say I'm completely fib free, but if you are even remotely entitled to the truth your going to get it. If I get caught lying I have to be OK with it and not care. That is a high bar.
This is a negotiation, they aren't entitled to know how much you make nor do they have a good method of checking up on it.