iOS Web Usage Over Twice as High as Android, Android Sales Numbers Called into Question

Daniel Eran Dilger, Apple Insider:

The fact that iOS is more than twice as popular on the web as all Android devices combined calls into question market statistics by research firms such as IDC, which recently stated that Apple's share of the tablet market had fallen to 43.6% of worldwide tablet sales. That report was presented by Adrian Covert of CNNMoney to state that "Android is the new king of tablet market share."

How does Android, with its reported huge sales and massive install base, make up for less than half the web browsing usage of iOS?