28. Operating leases

During the year ended 31 December 2017, $86m (2016: $84m, 2015: $77m) was recognised as an expense in the Group income statement in respect of operating leases, net of amounts borne directly by the System Fund. The expense includes contingent rents of $32m (2016: $32m, 2015: $29m). $2m (2016: $2m, 2015: $3m) was recognised as income from sub-leases.

Future minimum lease payments under non-cancellable operating leases are as follows:


	2017 $m		2016 $m
Due within one year		56		53
One to two years		46		49
Two to three years		45		43
Three to four years		60		41
Four to five years		30		58
More than five years		297		346

		534		590

In addition, in certain circumstances the Group is committed to making additional lease payments that are contingent on the performance of the hotels that are being leased.

The average remaining term of these leases, which generally contain renewal options, is approximately 15 years (2016: 17 years). No material restrictions or guarantees exist in the Group’s lease obligations.

Total future minimum rentals expected to be received under non-cancellable sub-leases are $4m (2016: $4m).