What is the sum of Year, when Regional GVA is 6,584, and when Services is less than 5,277?
CREATE TABLE "trend_of_regional_gross_value_added_of_c" (
  "year" real,
  "regional_gva" real,
  "agriculture" real,
  "industry" real,
  "services" real
);
SELECT SUM("year") FROM "trend_of_regional_gross_value_added_of_c" WHERE "regional_gva"='6,584' AND "services"<'5,277';