What is the minimum number of members Africa had in 2001?
CREATE TABLE "chronology_of_worldwide_membership" (
  "year" real,
  "worldwide" real,
  "africa" real,
  "america" real,
  "asia" real,
  "australia" real,
  "europe" real
);
SELECT MIN("africa") FROM "chronology_of_worldwide_membership" WHERE "year"=2001;