CREATE TABLE table_18545 ("District" TEXT, "Incumbent" TEXT, "Party" TEXT, "First elected" FLOAT, "Result" TEXT, "Candidates" TEXT)

Who was the incumbent in the Illinois 17 district?
SELECT "Incumbent" FROM table_18545 WHERE "District" = 'Illinois 17'
SELECT "Incumbent" FROM "table_18545" WHERE "District" = 'Illinois 17'