Maximum Speed on 2.4 GHz Wi-Fi with a 100 Mbps Backhaul

Hi Wi-Fi Experts.

One basic question: what is the maximum speed achievable on 2.4 GHz Wi-Fi if the backhaul connectivity is a 100 Mbps leased line (a real WAN connection from an ISP)?

Also, what percentage of the backhaul speed can the 2.4 GHz Wi-Fi realistically support?