What is the name of the building that was the tallest from 1990–1997 in Frankfurt?
CREATE TABLE "timeline_of_tallest_buildings" (
  "name" text,
  "city" text,
  "height_m" real,
  "height_ft" real,
  "floors" real,
  "years_as_tallest" text
);
SELECT "name" FROM "timeline_of_tallest_buildings" WHERE "city"='frankfurt' AND "years_as_tallest"='1990–1997';