March 2016 - IRIS v4.0 Released (current version)
Immaterial change. Minor revision to definition language for clarity.
March 2014 - IRIS v3.0 Released
Immaterial change. Minor revision to metric name and definition language for clarity.
November 2011 - IRIS v2.2 Released
February 2011 - IRIS v2.1 Released
September 2010 - IRIS v2.0 Released
New metric. Supplier Individuals: Urban (PI6179) developed via IRIS Taxonomy Development Group.