Annual purchase commitments under various contracts as of May 31, 2016 were as follows (in millions):

		Aircraft and
		Aircraft Related		Other⁽¹⁾		Total

2017		$	1,212	$	1,235	$	2,447
2018			1,770		401		2,171
2019			1,563		264		1,827
2020			1,620		193		1,813
2021			1,476		120		1,596
Thereafter			4,240		108		4,348
Total		$	11,881	$	2,321	$	14,202

⁽¹⁾	Primarily equipment, advertising contracts and, in 2017, approximately $615 million of estimated required quarterly contributions to our U.S. Pension Plans.

The amounts reflected in the table above for purchase commitments represent noncancelable agreements to purchase goods or services. As of May 31, 2016, our obligation to purchase four Boeing 767-300 Freighter (“B767F”) aircraft and seven Boeing 777 Freighter (“B777F”) aircraft is conditioned upon there being no event that causes FedEx Express or its employees not to be covered by the Railway Labor Act of 1926, as amended. Open purchase orders that are cancelable are not considered unconditional purchase obligations for financial reporting purposes and are not included in the table above.

We have several aircraft modernization programs underway that are supported by the purchase of B777F and B767F aircraft. These aircraft are significantly more fuel-efficient per unit than the aircraft types previously utilized, and these expenditures are necessary to achieve significant long-term operating savings and to replace older aircraft. Our ability to delay the timing of these aircraft-related expenditures is limited without incurring significant costs to modify existing purchase agreements.

During July 2015, FedEx Express entered into a supplemental agreement to purchase 50 additional B767F aircraft from Boeing. The 50 additional B767F aircraft are expected to be delivered from fiscal 2018 through fiscal 2023 and will enable FedEx Express to continue to improve the efficiency and reliability of its aircraft fleet.

On June 10, 2016, FedEx Express exercised options to acquire six additional B767F aircraft for delivery in 2019 and 2020.

We had $413 million in deposits and progress payments as of May 31, 2016 on aircraft purchases and other planned aircraft-related transactions. These deposits are classified in the “Other assets” caption of our consolidated balance sheets. Aircraft and aircraft-related contracts are subject to price escalations. The following table is a summary of the key aircraft we are committed to purchase as of May 31, 2016, with the year of expected delivery:

	B767F	B777F	Total

2017	12	-	12
2018	16	2	18
2019	13	2	15
2020	12	3	15
2021	10	3	13
Thereafter	16	6	22
Total	79	16	95