pre_text: 12. Derivative Instruments (a) Summary of Derivative Instruments We use derivative instruments primarily to manage exposures to foreign currency exchange rate, interest rate, and equity price risks. Our primary objective in holding derivatives is to reduce the volatility of earnings and cash flows associated with changes in foreign currency exchange rates, interest rates, and equity prices. Our derivatives expose us to credit risk to the extent that the counterparties may be unable to meet the terms of the agreement. We do, however, seek to mitigate such risks by limiting our counterparties to major financial institutions. In addition, the potential risk of loss with any one counterparty resulting from this type of credit risk is monitored. Management does not expect material losses as a result of defaults by counterparties. The notional amounts of our outstanding derivatives are summarized as follows (in millions):
table: July 27, 2019 July 28, 2018
table: Derivatives designated as hedging instruments:
table: Foreign currency derivatives—cash flow hedges $663 $147
table: Interest rate derivatives 4,500 6,750
table: Net investment hedging instruments 309 250
table: Derivatives not designated as hedging instruments:
table: Foreign currency derivatives 2,708 2,298
table: Total return swaps—deferred compensation 574 566
table: Total $8,754 $10,011
question: Analyse this data from a financial earnings document. What was the change in the Net investment hedging instruments between 2018 and 2019?