CREATE TABLE table_20991 ("Year" FLOAT, "Starts" FLOAT, "Wins" FLOAT, "Top 5" FLOAT, "Top 10" FLOAT, "Poles" FLOAT, "Avg. Start" TEXT, "Avg. Finish" TEXT, "Winnings" TEXT, "Position" TEXT, "Team ( s ) " TEXT)

Name the max top 5 for 5.0 avg finish
SELECT MAX("Top 5") FROM table_20991 WHERE "Avg. Finish" = '5.0'
SELECT MAX("Top 5") FROM "table_20991" WHERE "Avg. Finish" = '5.0'