CREATE TABLE "mixed_martial_arts_record" (
  "res" text,
  "record" text,
  "opponent" text,
  "method" text,
  "event" text,
  "round" real,
  "time" text,
  "location" text
);

Question: What is the round for the ufc on fox: velasquez vs. dos santos event?
SQL: SELECT AVG("round") FROM "mixed_martial_arts_record" WHERE "event"='ufc on fox: velasquez vs. dos santos';