pre_text: GasLog Ltd. and its Subsidiaries
  Notes to the consolidated financial statements (Continued)
  For the years ended December 31, 2017, 2018 and 2019
  (All amounts expressed in thousands of U.S. Dollars, except share and per share data) 26. Derivative Financial Instruments (Continued) The fair value of the derivative liabilities is as follows: Interest rate swap agreements The Group enters into interest rate swap agreements which convert the floating interest rate exposure into a fixed interest rate in order to hedge a portion of the Group’s exposure to fluctuations in prevailing market interest rates. Under the interest rate swaps, the bank counterparty effects quarterly floating-rate payments to the Group for the notional amount based on the U.S. dollar LIBOR, and the Group effects quarterly payments to the bank on the notional amount at the respective fixed rates. Interest rate swaps designated as cash flow hedging instruments As of December 31, 2018 and 2019, there are no interest rate swaps designated as cash flow hedging instruments for accounting purposes.
table: As of December 31,
table: 2018 2019
table: Derivative liabilities carried at fair value through profit or loss (FVTPL)
table: Interest rate swaps 9,196 49,891
table: Forward foreign exchange contracts 1,467 41
table: Derivative liabilities designated and effective as hedging instruments carried at fair value
table: Cross currency swaps 1,429 —
table: Total 12,092 49,932
table: Derivative financial instruments, current liability 2,091 8,095
table: Derivative financial instruments, non-current liability 10,001 41,837
table: Total 12,092 49,932
question: Analyse this data from a financial earnings document. What was the change in fair value of interest rate swaps from 2018 to 2019?