How many births per year are there for the period with 998 000 deaths per year?
CREATE TABLE "table1_18950570_2" (
  "period" text,
  "live_births_per_year" text,
  "deaths_per_year" text,
  "natural_change_per_year" text,
  "cbr" text,
  "cdr" text,
  "nc" text,
  "tfr" text,
  "imr" real,
  "life_expectancy_total" text,
  "life_expectancy_males" text,
  "life_expectancy_females" text
);
SELECT "live_births_per_year" FROM "table1_18950570_2" WHERE "deaths_per_year"='998 000';