pre_text: Other income (expense) nm—not meaningful Other income (expense), net changed $9.9 million in the year ended March 31, 2018 compared to the year ended March 31, 2017, which was primarily attributable to a change of $10.4 million in foreign exchange expense which was primarily attributable to the re-measurement of short-term intercompany balances denominated in currencies other than the functional currency of our operating units. The increase in interest income is primarily due to interest on investments.
table: Year ended March 31, Period-to-period change
table: % Change  2018 2017 Amount % Change
table: (dollars in thousands)
table: Other income (expense):                
table: Interest income $1,310 $510 $800 157%
table: Interest expense (598) (268) (330) 123%
table: Foreign exchange (expense) income and other, net   (3,439) 6,892 (10,331) nm 
table: Total other income (expense), net  $(2,727) $7,134 $(9,861) nm
question: Analyse this data from a financial earnings document. What is the average Interest expense for 2017 and 2018?