What is the largest base pair with a Strain of unspecified?
CREATE TABLE "list_of_sequenced_bacterial_genomes" (
  "species" text,
  "strain" text,
  "type" text,
  "base_pairs" real,
  "genes" real
);
SELECT MAX("base_pairs") FROM "list_of_sequenced_bacterial_genomes" WHERE "strain"='unspecified';