100GB for 30 years? Well, I'm not sure about average cases, but personally I have collected a stack of about a dozen of hard drives (volume ranging from 60GB to 2TB) over last 15 years. All fully loaded with the digital junk - because why delete things when you can just leave them?<p>Most of the data in that digital fossils is movies from that bay with pirates, but I guess there's still much more than 100GB of self-produced information - message (email, IM, phone) archives, digitized drawings, RAW photos, source code, savegames and so on.<p>Obviously, one could sort out the trash and compact the rest (like extracting a 10KB patch from several-gigabyte OpenWRT source tree, or radically compacting photo collection by deleting bad shots) and fit into 3GB/yr quota, but that's a hard and - unless one really wishes to fit some storage quota instead of just buying another hard drive - mostly pointless work.