X Company must purchase a new delivery truck and is using the payback method to evaluate two possible trucks. Truck X costs $30,000; Truck Y costs $51,000. The useful life of both is seven years, with the following estimated operating cash flows:

Year	Truck X	Truck Y
1	$-6,000	$-7,000
2	-8,000	-4,000
3	-8,000	-3,000
4	-8,000	-3,000
5	-6,000	-3,000
6	-5,000	-2,000
7	-4,000	-2,000

If X Company chooses Truck Y instead of Truck X, what is the payback period (in years)?