[Skrooge] Expenses relative to net income

I’m not sure how can I configure a report to show my expenses (without taxes) relative to my net income. I pay all my taxes on my own and I don’t know how to differentiate them from my normal expenses.

Gross income: 1000
Taxes: -300
Net income: 700
Expenses: -500
Money left: 200

I would like to see that I spent 500 out of 700 that is 71% of my net income. But if taxes and normal expenses are treated equally than it will be 800 out of 1000 which is 80% of gross income.