CREATE TABLE table_69484 ("Low Estimate" FLOAT, "High Estimate" FLOAT, "Type" TEXT, "Location" TEXT, "Date" TEXT)

What is the sum of low estimate(s) that is listed for the date of 1978?
SELECT SUM("Low Estimate") FROM table_69484 WHERE "Date" = '1978'
SELECT SUM("Low Estimate") FROM "table_69484" WHERE "Date" = '1978'