pre_text: GreenSky, Inc. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued) (United States Dollars in thousands, except per share data, unless otherwise stated) Disaggregated revenue Revenue disaggregated by type of service was as follows for the periods presented: (1) For the year ended December 31, 2019, includes a $30,459 change in fair value of our servicing asset primarily associated with increases to the contractually specified fixed servicing fees for certain Bank Partners. Refer to Note 3 for additional information. (2) Other revenue includes miscellaneous revenue items that are individually immaterial. Other revenue is presented separately herein in order to clearly present merchant, interchange and servicing fees, which are more integral to our primary operations and better enable financial statement users to calculate metrics such as servicing and merchant fee yields. No assets were recognized from the costs to obtain or fulfill a contract with a customer as of December 31,
  2019 and 2018. We recognized bad debt expense arising from our contracts with customers of $950, $1,294 and
  $817 during the years ended December 31, 2019, 2018 and 2017, respectively, which is recorded within general and
  administrative expense in our Consolidated Statements of Operations.
table: Year Ended December 31,
table: 2019 2018 2017
table: Merchant fees $361,755 $297,776 $234,548
table: Interchange fees 44,150 51,128 44,410
table: Transaction fees 405,905 348,904 278,958
table: Servicing fees(1) 123,697 65,597 46,575
table: Other(2) 44 172 354
table: Servicing and other 123,741 65,769 46,929
table: Total revenue $529,646 $414,673 $325,887
question: Analyse this data from a financial earnings document. What was the change in the transaction fees between 2017 and 2019?