CREATE TABLE table_57890 ("Year" FLOAT, "Association" TEXT, "Category" TEXT, "Nominated work" TEXT, "Result" TEXT)

Who won the most recent favorite rap/hip-hop new artist at the American music awards?
SELECT MAX("Year") FROM table_57890 WHERE "Association" = 'american music awards' AND "Category" = 'favorite rap/hip-hop new artist'
SELECT MAX("Year") FROM "table_57890" WHERE "Association" = 'american music awards' AND "Category" = 'favorite rap/hip-hop new artist'