CREATE TABLE inst (instid DECIMAL, name TEXT, country TEXT)
CREATE TABLE papers (paperid DECIMAL, title TEXT)
CREATE TABLE authorship (authid DECIMAL, instid DECIMAL, paperid DECIMAL, authorder DECIMAL)
CREATE TABLE authors (authid DECIMAL, lname TEXT, fname TEXT)

Retrieve the country that has published the most papers.
SELECT t1.country FROM inst AS t1 JOIN authorship AS t2 ON t1.instid = t2.instid JOIN papers AS t3 ON t2.paperid = t3.paperid GROUP BY t1.country ORDER BY COUNT(*) DESC LIMIT 1
SELECT "t1"."country" FROM "inst" AS "t1" JOIN "authorship" AS "t2" ON "t1"."instid" = "t2"."instid" JOIN "papers" AS "t3" ON "t2"."paperid" = "t3"."paperid" GROUP BY "t1"."country" ORDER BY COUNT(*) DESC NULLS LAST LIMIT 1