I've never gotten any sort of notification for downloading in my two decades or so using the internet. Keep in mind I'm also not posting about it somewhere super public like Facebook.
Generally, if your ISP is going to send you a letter there are 2 causes. Public file sharing without checking the sources, and large amounts of upload bandwidth which indicates seeding torrents or otherwise hosting file-sharing.
To check your torrents try to find a sight that posts DMCA removal on the search results page, or find a link that posts the Hash code before you start downloading. You can then google the hash code and scroll to the bottom to see if Google lists a DMCA removal. If it does list a DMCA removal, that file is being watched and is probably hosted on a hostile computer. That makes finding the ISP of each downloader automatic.
If you live in area where large uploads are tracked, don't seed. This will limit you to public sources since private sources usually require a high ratio of upload:download time.
Be afraid. Be very afraid.
please give about an estimate or rough sum or exact if you know it just curious about how much people actually download using these sites im olnt at about 1.6GB total