What period was the life expectancy at 62.4?
CREATE TABLE "table1_27434_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 "period" FROM "table1_27434_2" WHERE "life_expectancy_total"='62.4';