Gateway Load Balancer in python

I have a list of payment gateways. The problem is I need to find out the which gateway I need to send right now. I have two dict. payment_count = {'first_g':0, 'sec_g':0} --> while select the gateway we will update gateway_percentage = {'first_g':80, 'sec':20 } ---> static I need to find which gateway i need to select , when ever request comes finally we will update the payment_cout dict