pre_text: Note 11. Share-Based Compensation A summary of share-based compensation expense recognized in the Company’s Consolidated Statements of Operations is as follows (in thousands):
table: Year ended December 31,
table: 2019 2018 2017
table: Cost of revenues $8,741 $4,982 $3,735
table: Research and development 23,132 14,975 9,550
table: Sales and marketing 38,325 27,324 16,015
table: General and administrative 31,156 20,807 12,760
table: Total share-based compensation expense $101,354 68,088 42,060
question: Analyse this data from a financial earnings document. What is the average share-based compensation expense spent on sales and marketing per year between 2017 to 2019?