Table:
|  | 2019 | 2018 | 2017 |
| --- | --- | --- | --- |
| Moody’s / S&P credit rating of counterparty | £m | £m | £m |
| Aa2/AA and above | 2,522 | 2,575 | 1,444 |
| Aa3/AA– | 1,376 | 313 | 208 |
| A1/A+a | 1,145 | 651 | 952 |
| A2/Aa | 649 | 628 | 370 |
| A3/A–a | 50 | 180 | 204 |
| Baa1/BBB+a | 75 | 59 | 561 |
| Baa2/BBB and below a | 160 | 207 | 86 |
|  | 5,977 | 4,613 | 3,825 |
Paragraphs:
The credit quality and credit concentration of cash equivalents, current asset investments and derivative financial assets are detailed in the tables below. Where the opinion of Moody’s and Standard & Poor’s (S&P) differ, the lower rating is used.
a We hold cash collateral of £638m (2017/18: £492m, 2016/17: £702m) in respect of derivative financial assets with certain counterparties.
The concentration of credit risk for our trading balances is provided in note 17, which analyses outstanding balances by customerfacing unit. Where multiple transactions are undertaken with a single financial counterparty or group of related counterparties, we enter into netting arrangements to reduce our exposure to credit risk by making use of standard International Swaps and Derivatives Association (ISDA) documentation.
We have also entered into credit support agreements with certain swap counterparties whereby, on a daily, weekly and monthly basis, the fair value position on notional £3,289m of long dated cross-currency swaps and interest rate swaps is collateralised. The related net cash inflow during the year was £129m (2017/18: outflow £220m, 2016/17: inflow £100m). The collateral paid and received is recognised within current asset investments and loans and other borrowings, respectively.
Question:
What is the average Aa3/AA– for 2017-2019?
Answer: (1376 + 313 + 208) / 3 = 632.33