There are plenty of websites on the internet that will test your clicking speed. The average click speed is about 6 clicks per second (CPS). A fast clicker can click at about 9-12 clicks per second.
This takes time to get good at. Use click speed testers, and try jitter-clicking in-game. Whenever you have an unplugged mouse, try jittering for a couple of seconds at a time. Eventually, it will become natural. If you succeed, then you should get around 7-9. If you become a master, you might reach 12 cps. Good Luck!