What is the largest overall number of major hurricanes?
CREATE TABLE "1860s" (
  "year" real,
  "number_of_tropical_storms" real,
  "number_of_hurricanes" real,
  "number_of_major_hurricanes" real,
  "deaths" text,
  "strongest_storm" text
);
SELECT MAX("number_of_major_hurricanes") FROM "1860s";