pre_text: The following table presents total stock-based compensation cost included in income from continuing operations. Total unrecognized compensation cost related to non-vested awards at December 31, 2019 was $1.2 billion and is expected to be recognized over a weighted-average period of approximately 2.5 years. Capitalized stock-based compensation cost was not material at December 31, 2019, 2018 and 2017.
table: ($ in millions)
table: For the year ended December 31: 2019 2018 2017
table: Cost $100 $82 $91
table: Selling, general and administrative 453 361 384
table: Research, development and engineering 126 67 59
table: Pre-tax stock-based compensation cost 679 510 534
table: Income tax benefits (155) (116) (131)
table: Net stock-based compensation cost $524 $393 $403
question: Analyse this data from a financial earnings document. What is the average Selling, general and administrative?