What is the fewest number of wins in the chart for Ayrton Senna?
CREATE TABLE "most_wins_in_a_season" (
  "driver" text,
  "season" text,
  "wins" real,
  "entries" text,
  "percentage" text
);
SELECT MIN("wins") FROM "most_wins_in_a_season" WHERE "driver"='ayrton senna';