Yes this is correct. Those numbers are based on data published at http://www.newvem.com/topic/cloud-radar. For reference, light user are those with up to 8 instances, medium users have between 9 and 35 instances, and heavy users above 35. We didn't publish the total number of users in each segment, but I can confirm that that the survey was based on a sample of around 200 customers, as mentioned in GigaOm's article
The reason we chose to segment by number of instances is that we consider this as a good metric for the complexity of one's cloud footprint, and the corresponding effort required to manage this footprint.
The reason we chose to segment by number of instances is that we consider this as a good metric for the complexity of one's cloud footprint, and the corresponding effort required to manage this footprint.