Xiaoming had four different set-ups, W, X, Y and Z, each with a different number of bulbs connected in series in a circuit. All the bulbs were similar and the number of batteries used was the same in the circuit.
He recorded the brightness of each bulb as shown in the table below.
|Brightness of each bulb (units)||3||7||2||5|
Arrange the set-ups with the most number of bulbs at the top to the least number of bulbs at the bottom.