Some countries were not included for various reasons, mainly the unavailability of certain crucial data. The following United Nations Member States were not included in the 2011 report: North Korea, Marshall Islands, Monaco, Nauru, San Marino, South Sudan, Somalia and Tuvalu.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): What is the main reason that countries were excluded from the 2011 report?
unavailability of certain crucial data