IBM published an e-book Understanding Big Data: Analytics for Enterprise Class Hadoop and Streaming Data and here are some highlights:

• 90% of the data in the world today has been created in the last two years alone.
• 1 in 3 business leaders don’t trust the information they use to make decisions.

Every day:

• We create 2.5 quintillion bytes of data.
• 12 terabytes of Tweets.
• 5 million trade events
• 500 million daily call detail records.