I recently switched ISP's and did it through my phone so I ended up with the app on my phone. I don't recall ever logging in with my previous provider so I never checked the data usage. I was frequently checking it this time around (since it was just a click away) and I was shocked at how much we ended up using.
Last month we had used over 9TB (upload and download). I was downloading more frequently this time around but I have a big online backup running nightly so it can't have impacted my usage too much. If I was being modest even without the frequent download I would guess that I used 5-7TB monthly before this.
This seems like a lot to me so I'm just wondering how much others are using.