What is the average grid for vehicles manufactured by Aprilia and having run more than 16 laps?
CREATE TABLE "125cc_classification" (
  "rider" text,
  "manufacturer" text,
  "laps" real,
  "time" text,
  "grid" real
);
SELECT AVG("grid") FROM "125cc_classification" WHERE "manufacturer"='aprilia' AND "laps">16;