Confirmed Answer: 12 to 18 months
From the Odyessyware passage:
Although a tremendous number of changes have occurred in the past twenty years, it is only the beginning. Depending on the source you read, it is estimated that human knowledge doubles every 12 to 18 months! Think about it. Everything we have ever learned about—from the discovery of fire to the invention of computers—pales in comparison to how much is being learned today.
