CREATE TABLE table_8359 ("Date" TEXT, "Name of ship" TEXT, "Nationality" TEXT, "Tonnage" FLOAT, "Fate" TEXT)

What was the average tonnage for the Siljan ship from Sweden?
SELECT AVG("Tonnage") FROM table_8359 WHERE "Nationality" = 'sweden' AND "Name of ship" = 'siljan'
SELECT AVG("Tonnage") FROM "table_8359" WHERE "Name of ship" = 'siljan' AND "Nationality" = 'sweden'