Add data and diagrams for ratios of participations per country/chapter

This is a work in progress: the diagrams in the second sheet were copied
from the first sheet and did not update automatically as the data was
replaced. Since custom styling of these diagrams takes a lot of time,
I will probably edit the data of each diagram by hand instead (which
is also a painfully long process... because cut and paste is only
allowed cell by cell, and done in a modal window from which the
rest of Calc, any spreadsheet, is unavailable...)