What was the minimum % funded of the project that was closed on 2012-05-18?
CREATE TABLE "ten_largest_successfully_completed_kicks" (
  "rank" real,
  "total_usd" real,
  "project_name" text,
  "creator" text,
  "category" text,
  "pct_funded" real,
  "backers" real,
  "closing_date" text
);
SELECT MIN("pct_funded") FROM "ten_largest_successfully_completed_kicks" WHERE "closing_date"='2012-05-18';