What was the largest index the year/s forcible rapes numbered 1084? 
CREATE TABLE "crime_statistics_1960_2009" (
  "year" real,
  "population" real,
  "index" real,
  "violent" real,
  "property" real,
  "murder" real,
  "forcible_rape" real,
  "robbery" real,
  "aggravated_assault" real,
  "burglary" real,
  "larceny_theft" real,
  "vehicle_theft" real
);
SELECT MAX("index") FROM "crime_statistics_1960_2009" WHERE "forcible_rape"=1084;