Some numbers from E-learning Guild 360° report on learning systems

• The top ten vendors enjoy a 70% market share and the top 20 vendors an 83% market share.
• 'Developed in house' is the second largest LMS in terms of market share, with a market penetration of 12.78%. Moodle, the most popular open source LMS, comes 4th but is usually a secondary LMS. (These numbers include academia and small companies as well as large enterprises.)
  
• Costs per learner per year for large corporations (> 5000) for the LMS vary from 15$ to 57$.