How many people were in the crowd when the home team scored 31.9 (195)?
CREATE TABLE "round_18" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);
SELECT COUNT("crowd") FROM "round_18" WHERE "home_team_score"='31.9 (195)';