I average about 23GB a month and I wouldn't say I'm a heavy user. I don't really use social media so it's mostly Reddit, internet use, Streaming apps (youtube/nowtv) or Apple Music. My highest recent month is 37GB but I think I used the tethered connection a fair bit that month.
Dude, that's well above average and well into the 'heavy user' category (not top 1% mind). Most normal's have under 10GB on their contracts. It's pretty difficult to get above 5GB unless you are you are either very heavy into social media, streaming audio/video or tethering.
https://www.ispreview.co.uk/index.p...ile-users-wasting-3-4gb-data-every-month.html
Average usage is 2.5GB/month. In 2017 Ofcom said the average was 1.9GB/month.