What is the lowest Natural Change, when Natural Change (Per 1000) is 19.1, and when Crude Birth Rate (Per 1000) is less than 28.3?
CREATE TABLE "vital_statistics" (
  "average_population_x_1000" real,
  "live_births" real,
  "deaths" real,
  "natural_change" real,
  "crude_birth_rate_per_1000" real,
  "crude_death_rate_per_1000" real,
  "natural_change_per_1000" real
);
SELECT MIN("natural_change") FROM "vital_statistics" WHERE "natural_change_per_1000"=19.1 AND "crude_birth_rate_per_1000"<28.3;