 how many countries sampled with year of publication being 2007 and ranking l.a. (2) being 7th
CREATE TABLE "table" (
  "index_year" text,
  "author_editor_source" text,
  "year_of_publication" text,
  "countries_sampled" real,
  "world_ranking_1" text,
  "ranking_l_a_2" text
);
SELECT COUNT("countries_sampled") FROM "table" WHERE "year_of_publication"='2007' AND "ranking_l_a_2"='7th';