How many Years have Ratings of 10.9/23?
CREATE TABLE "fox_nbc_era_2001_2006" (
  "year" real,
  "network" text,
  "lap_by_lap" text,
  "s_color_commentator" text,
  "pre_race_host" text,
  "ratings" text
);
SELECT COUNT("year") FROM "fox_nbc_era_2001_2006" WHERE "ratings"='10.9/23';