How long was the 16 staged event in 1997?
CREATE TABLE "marlboro_tour" (
  "year" text,
  "name" text,
  "date" text,
  "stages" text,
  "distance" text,
  "winner" text,
  "time" text
);
SELECT "distance" FROM "marlboro_tour" WHERE "stages"='16' AND "year"='1997';