pre_text: Summarised cash flow statement Cash flow We generated a net cash inflow from operating activities of £4,256m, down £671m, mainly driven by £2bn contributions to the BT Pension Scheme, offset by favourable working capital movements. In line with our outlook, normalised free cash flowb was £2,440m, down £533m or 18%, driven by increased cash capital expenditure, decrease in EBITDA and higher tax payments. Free cash flow, which includes specific item outflows of £598m (2017/18: £828m) and a £273m (2017/18: £109m) tax benefit from pension deficit payments, was £619m (2017/18: £1,586m). Last year also included payments of £325m for the acquisition of mobile spectrum. The spectrum auction bidding took place across the 2017/18 and 2018/19 financial years. Whilst £325m was on deposit with Ofcom at 31 March 2018, we went on to acquire spectrum for a total price of £304m and the excess deposit balance has since been refunded. We made pension deficit payments of £2,024m (2017/18: £872m) and paid dividends to our shareholders of £1,504m (2017/18: £1,523m). The net cash cost of specific items of £598m (2017/18: £828m) includes restructuring payments of £372m (2017/18: £189m) and regulatory payments of £170m (2017/18: £267m). Last year also included payments of £225m relating to the settlement of warranty claims under the 2015 EE acquisition agreement. b After net interest paid, before pension deficit payments (including the cash tax benefit of pension deficit payments) and specific items.
table: 2019 2018 2017
table: Year ended 31 March £m £m £m
table: Cash generated from operations 4,687 5,400 6,725
table: Tax paid (431) (473) (551)
table: Net cash inflows from operating activities 4,256 4,927 6,174
table: Net purchase of property, plant and equipment and software (3,637) (3,341) (3,119)
table: Free cash flow 619 1,586 3,055
table: Interest received 23 7 7
table: Interest paid (531) (555) (629)
table: Add back pension deficit payments 2,024 872 274
table: Add back net cash flow from specific items 598 828 205
table: Add back net sale of non-current asset investments 1 19 (20)
table: Add back prepayments in respect of acquisition of spectrum licence - 325 -
table: Remove refund on acquisition of spectrum licence (21) - -
table: Remove cash tax benefit of pension deficit payments (273) (109) (110)
table: Normalised free cash flow b 2,440 2,973 2,782
question: Analyse this data from a financial earnings document. What is the average tax paid for 2017-2019?