What is the average regular number of attendees that has 79 parishes?
CREATE TABLE "by_jurisdiction_in_the_usa" (
  "adherents" real,
  "regular_attendees" real,
  "pct_of_adherents" text,
  "monasteries" real,
  "parishes" real,
  "average_parish_size" real
);
SELECT AVG("regular_attendees") FROM "by_jurisdiction_in_the_usa" WHERE "parishes"=79;