pre_text: Share-Based Compensation The following table shows a summary of share-based compensation expense included in the Consolidated Statements of Operations during the periods presented (in thousands): Amounts presented above include share-based compensation expense of $0.8 million for fiscal year 2017, which is recorded as discontinued operations related to employees of our Compute business. As of September 27, 2019, the total unrecognized compensation costs related to outstanding stock options, restricted stock awards and units including awards with time-based, performance-based, and market-based vesting was $47.0 million, which we expect to recognize over a weighted-average period of 2.9 years.
table: Fiscal Years
table: 2019 2018 2017
table: Cost of revenue $2,936 $3,869 $3,189
table: Research and development 8,551 13,448 10,565
table: Selling, general and administrative 12,305 14,620 22,581
table: Total $23,792 $31,937 $36,335
question: Analyse this data from a financial earnings document. What was the average cost of revenue for 2017-2019?