Docebo published a wonderful report sometime back. It is available at this location: https://docebo.com/landing/contactform/elearning-market-trends-and-forecast-2014-2016-docebo-report.pdf
Based on this report, the total e-learning market size is going to be $51.5 Billion by 2016. Also, the annual world-wide growth rate over the period of 2012-2016 is pegged at 7.9%. This report also provides a break-down by continents, and provides the expected revenue, and growth rates in individual markets.
Currently, the e-learning industry is dominated by K-12, and Higher education based LMS, and content solutions. Corporate e-learning is on the rise, and is growing at an average CAGR of 12%.