What is the sum of low estimate(s) that is listed for the date of 1978?
CREATE TABLE table_name_66 (low_estimate INTEGER, date VARCHAR)
SELECT SUM(low_estimate) FROM table_name_66 WHERE date = "1978"
### Context: CREATE TABLE table_name_66 (low_estimate INTEGER, date VARCHAR) ### Question: What is the sum of low estimate(s) that is listed for the date of 1978? ### Answer: SELECT SUM(low_estimate) FROM table_name_66 WHERE date = "1978"