pre_text: Share Based Compensation Expense Share-based compensation expense recognized in the financial statements by line item caption is as follows (in thousands): The amount of share-based compensation expense capitalized in inventory has been immaterial for each of the periods presented.
table: Year Ended
table: June 30,
  2019 June 30,
  2018 June 30,
  2017
table: Cost of product revenue  $844 $564 $333
table: Cost of service revenue 1,639 1,131 589
table: Research and development   10,443 7,642 3,312
table: Sales and marketing   11,747 9,843 4,253
table: General and administrative   8,224 8,453 4,146
table: Total share-based compensation expense  $32,897 $27,633 $12,633
question: Analyse this data from a financial earnings document. What was the change in cost of product revenue between 2018 and 2019?