What's listed for the Turnout % with a Ngilu of 30,535?
CREATE TABLE "by_province" (
  "province" text,
  "kibaki" text,
  "raila" text,
  "wamalwa" text,
  "ngilu" text,
  "others" text,
  "registered_voters" text,
  "turnout_pct" text
);
SELECT "turnout_pct" FROM "by_province" WHERE "ngilu"='30,535';