Simple:

ldapsearch -LLLL -h db.debian.org -W -D'uid=lars,ou=users,dc=debian,dc=org' -x -b'ou=users,dc=debian,dc=org' '(c=*)' c | sort | uniq -c

(obviously all on one line, but my mdwn skillz are nonexistent)

that should get you a count of number of developers per country...