5o-80 GB was download - mostly IIT lectures and rest upload. there was a bug in my ISP or maybe in my connection and i was not getting charged for my internet. Now that bug is no more so I am just in 10 GB plan
I use between 3 to 6 Gb download and 1 to 3 upload. Working with 2 or 3 pdf's per day increases a lot bandwith use. I have a 5Gb. plan but when reached limit it only limits speed to 128Kbps what is usually enough.