“Estimating that is a fairly difficult task, but one person made an estimate not so long ago who can probably be trusted to have a good idea. Eric Schmidt, the CEO of Google, the world’s largest index of the Internet, estimated the size at roughly 5 million terabytes of data. That’s over 5 billion gigabytes of data, or 5 trillion megabytes. Schmidt further noted that in its seven years of operations, Google has indexed roughly 200 terabytes of that, or .004% of the total size.”
http://www.wisegeek.com/how-big-is-the-internet.htm
The web's content has grown by literally orders of magnitude since then.
BTW, being something of a proper-English nut, I hate it when people use the terms "literally" and "order of magnitude" improperly. But the above is indeed true (at least 10^2), so I'll take the grammar risk.
If the google quote is right, 5,000,000,000 TB, then even my statement falls short by many orders of magnitude.