CREATE TABLE table_759 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

What year was first elected william m. wheeler (d) unopposed?
SELECT "First elected" FROM table_759 WHERE "Candidates" = 'William M. Wheeler (D) Unopposed'
SELECT "First elected" FROM "table_759" WHERE "Candidates" = 'William M. Wheeler (D) Unopposed'