CREATE TABLE "nascar_sprint_cup_series" (
  "year" text,
  "starts" real,
  "wins" real,
  "top_5" real,
  "top_10" real,
  "poles" real,
  "avg_start" real,
  "avg_finish" real,
  "winnings" text,
  "position" text,
  "team_s" text
);

Question: How many times did the team with an average start of 18.9 make the top 10?
SQL: SELECT SUM("top_10") FROM "nascar_sprint_cup_series" WHERE "avg_start"=18.9;