About: http://webisa.webdatacommons.org/450340839

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	His study showed that the cost of a lumen had declined by a factor of almost 400 since 1800.The study is a bit of a slog, but it is worth looking at the tables and graphs.
http://www.w3.org/ns/prov#wasQuotedFrom	blogspot.com