€ / mln 2017 2016
Revenue 5,973 5,484
Toll revenue 4,195 4,009
Airport service revenues 799 636
Other operating income and contract revenue 979 839
Gross operating profit (EBITDA) 3,664 3,378
Gross operating profit (EBITDA) adjusted (a) 3,762 3,469
Operating profit (EBIT) 2,578   2,315
Profit before tax from continuing operations 2,065 1,776
Profit for the year 1,432 1,238
Profit for the year attributable to owners of the parent 1,172 1,122
FFO- Operating cash flow (b) 2,540 2,400
FFO- Operating cash flow adjusted (a) 2,586 2,439
Capital expenditure (c) 1,050 1,422
Equity 11,763 9,923
Equity attributable to owners of the parent 8,772 7,224
Net debt 9,496 11,677
Net debt adjusted (a) 10,577 12,823

(a) Adjusted amounts have been presented with the aim of enabling analysts and the rating agencies to assess the Group’s results of operations and financial position using the basis of presentation normally adopted by them.

(b) Operating cash flow is calculated as profit for the year + amortisation/depreciation +/- impairments/reversals of impairments of assets +/- provisions/releases of provisions + other adjustments + financial expenses from discounting of provisions +/- share of profit/(loss) of investees accounted for using equity method +/- (losses)/gains on sale of assets +/- other non-cash items +/- net deferred tax assets/liabilities recognised in profit or loss.

 (c) The figure includes investment in assets held under concession, in property, plant and equipment and in intangible assets.