Lets Create Space

I was wondering - how much of electronic data space would be there in this world. And how much of it is being underutilized (or may be overutilized from another perspective)?
We as individuals and organizations store lot of un necessary data in the name of backup. And we do take backup of backup, email data to multiple email accounts, copy in network and write in CD/DVDs

Just imagine the amount of free space the world could achieve, if we delete the unnecessary backups, unnecessary emails and junk data !!

Ofcourse not a good idea for companies manufacturing storage devices and disks ;)