What percentage of users were using Safari during the period in which 30.82% were using Firefox?
CREATE TABLE "usage_share_data_from_wikimedia_visitor_" (
  "period" text,
  "internet_explorer" text,
  "firefox" text,
  "chrome" text,
  "safari" text,
  "opera" text,
  "other_mozilla" text,
  "mobile" text
);
SELECT "safari" FROM "usage_share_data_from_wikimedia_visitor_" WHERE "firefox"='30.82%';