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) 15. Vessel Operating and Supervision Costs An analysis of vessel operating and supervision costs is as follows:
table: For the year ended December 31,
table: 2017 2018 2019
table: Crew wages and vessel management employee costs 72,652 79,624 80,713
table: Technical maintenance expenses 28,736 28,694 37,653
table: Other vessel operating expenses 21,098 19,766 21,296
table: Total 122,486 128,084 139,662
question: Analyse this data from a financial earnings document. What was the change in technical maintenance expenses from 2017 to 2018?