Export of Authors with Cumulated Contribution Codes for Funnel Filtering

A Contribution Code is computed for each participation by concatenating
numeric identifiers, separated by periods, in the following order:

* assessment report number
* working group number
* role identifier
* institution (minimum) identifier
* country identifier

In Cumulated Contribution Codes, only distinct Contribution Codes are
listed for each author, with the contributions with the same code
appended to the code, after the separator '.x', for example:
(Contribution Code).x2 for a (Contribution Code) corresponding
to two different participations of an author.