What is the % of same-sex marriages for the year of 2011?
CREATE TABLE "marriage_statistics" (
  "year" text,
  "marriages_between_men" real,
  "marriages_between_women" real,
  "same_sex_marriages" real,
  "total_marriages" real,
  "pct_same_sex_marriages" text
);
SELECT "pct_same_sex_marriages" FROM "marriage_statistics" WHERE "year"='2011';