About: http://webisa.webdatacommons.org/103686288

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Knowing that the official measure was devised in the 1960s and has not essentially changed since then other than adjustments for inflation provides a clue.
http://www.w3.org/ns/prov#wasQuotedFrom	wisc.edu