What is the Speed when Construction begun in 2010, and an Expected start of revenue services of 2015?
CREATE TABLE "bulgaria" (
  "line" text,
  "speed" text,
  "length" text,
  "construction_begun" text,
  "expected_start_of_revenue_services" real
);
SELECT "speed" FROM "bulgaria" WHERE "construction_begun"='2010' AND "expected_start_of_revenue_services"=2015;