Merchant Fees (credit and debit cards)

Do you know roughly what percentage of your backpackers use a booking site? and also when they come to pay what percentage pay the remaining balance with a card? I’m mainly interested in European hostels, but don't mind hearing from others.

I'm trying to work out possible fees for profit/loss projections.

I’m going to guess around 50% for both, would you say this a fair assumption or wildly out these days?

Thanks