What is the percent for when against prohibition is 2978?
CREATE TABLE "results_of_the_national_referendum_on_pr" (
  "jurisdiction" text,
  "for_prohibition" real,
  "percent_for" text,
  "against_prohibition" real,
  "percent_against" text
);
SELECT "percent_for" FROM "results_of_the_national_referendum_on_pr" WHERE "against_prohibition"=2978;