"They say many companies do not even know they have been breached." This is the scariest fact of the whole article. We hear about Sony, Target, Home Depot, etc

"They say many companies do not even know they have been breached." This is the scariest fact of the whole article. We hear about Sony, Target, Home Depot, etc. on the news, but how many others are out there that we don't know about? Dozens? Hundreds?