With Linkedin - how far back do you go...?

I have a question as a result of some wondering this morning, how far back on LinkedIn should your career/role history go? Its a bit like the CV question of how many previous jobs to list but without any page length constraints. My personal history goes back to 1998, which is a consciously unconscious choice - basically because I joined Linkedin in around 2004 only 18 months or so after it launched (hence why I was able to have my name as my handle) and at that time it was only 6 years of history and since then I have simply added new jobs on top without much thought about "archiving" old ones. Apart from for curiosity value I'm not sure seeing where I was working 21 years ago (!!!) is that relevant to today, but equally a little bit of me now wants to keep it there - its a bit like those boxes you have when moving houses, they move from loft/garage to next loft/garage and don't get opened but you have a niggle about simply throwing it away even though for many, many years you haven't once looked in them. What is a good cut off? Number of roles or duration of time? Or just go with it and list it all - back to the those very first jobs? (Which for me are not listed - my time spent and roles at amongst others TSB and Sainsburys will remain a mystery.)