This latest version (0.3), besides computing first place finish percentage for a single webpage, also keeps track of all pages a user visits and calculates the accumulated (total) first place finish percentage for each task type (subproject) and user or host computer.
The extension now features a context sensitive popup menu which allows the user to enable/disable the add-on and also reset the acumulated total first finish percentage figures. The reset of the accumulated total can be done for all task types or for individual combinations of task type and user/ host (according to the webpage from where the popup menu is invoked).

A toolbar button has been added.
It's now possible to disable the add-on.
When disabled, the add-on forces a reload of all the tabs in which the 1st place percentage was added.