Querying Discount Endpoint on discountPercent

Can somebody show me the query to find all precentage discounts?
I need all discounts that have discountPercent > 0. When I use the normal query
Discount.json?discountPercent=%3E%2C0
it will return a server error
500 => An error has occurred and we've been notified. Please try again and if this problem persists please contact support.
Same error for discountAmount = 0
Discount.json?discountAmount=%3D%2C0
And even the same when trying
Discount.json?discountAmount=0