fmt.Println prints out format verbs like %s

I've written code that is intended to print out keys and values in a map.

kvs := map[string]string{"a": "apple", "b": "banana"}
for k, v := range kvs {
    fmt.Println("%s -> %s\n", k, v)
}

I'm expecting the output to be:

a -> apple
b -> banana

But the output is actually:

%s -> %s
a apple
%s -> %s
b banana