CREATE TABLE table_12389 ("Year" FLOAT, "Gold" TEXT, "Silver" TEXT, "Bronze" TEXT, "Notes" TEXT)

What is Silver, when Notes is '6.24km, 23controls'?
SELECT "Silver" FROM table_12389 WHERE "Notes" = '6.24km, 23controls'
SELECT "Silver" FROM "table_12389" WHERE "Notes" = '6.24km, 23controls'