CREATE TABLE table_18335 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

What year was incumbent mark w. hannaford elected?
SELECT MIN("First elected") FROM table_18335 WHERE "Incumbent" = 'Mark W. Hannaford'
SELECT MIN("First elected") FROM "table_18335" WHERE "Incumbent" = 'Mark W. Hannaford'