List ordered by year with number of joined countries + total + enumeration of countries.

omgc-may-9-2.cypher

MATCH (c:Country)-[:JOINED_AT]->(y:Year)
WITH y.value as year, apoc.coll.sort(collect(c.name)) as cs
WITH year, reduce(r = "", x IN cs | CASE WHEN r = "" THEN x ELSE (r + ", " + x) END) as desc, reduce(n = 0, x IN cs | n + 1) as num
WITH collect({ year: year, num: num, desc: desc }) as all
WITH all, reduce(s = 0, x IN all | s + x.num) as total
WITH apoc.coll.union(all, [{ year: "Total", num: total, desc: "" }]) as result
UNWIND result as item
RETURN item.year as year, item.num as countriesJoined, item.desc as countries
ORDER BY item.year