~80% when you step out of wifi range on your cell phone.

… from 0% (a wired home LAN with nothing screwy going on) to 100% (e.g., cell reception at the San Antonio Caltrain station), depending on conditions…?

As it always has been, and always will be.

It can be high on cellular.

Pretty bad sometimes when on a train

That depends on how much data you are pushing. if you are pushing 200 mb on a 100mb line you will get 50% packet loss.