Changes in Version 8.1-1 o Updated documentation after R package "pwt9" was released for PWT 9.0. Changes in Version 8.1-0 o Update for PWT 8.1 (originally released in April 2015). It is an updated version of PWT 8.0, covering the same countries and period. Changes in Version 8.0-0 o New package pwt8 for PWT 8.x. So far only PWT 8.0 has been released (in July 2013) and has been added as pwt8.0.