pre_text: NOTE 7 — PROPERTY AND EQUIPMENT The components of property and equipment were as follows: During fiscal years 2019, 2018, and 2017, depreciation expense was $9.7 billion, $7.7 billion, and $6.1 billion, respectively. We have committed $4.0 billion for the construction of new buildings, building improvements, and leasehold improvements as of June 30, 2019.
table: (In millions)
table: June 30, 2019 2018
table: Land $ 1,540 $ 1,254
table: Buildings and improvements 26,288 20,604
table: Leasehold improvements 5,316 4,735
table: Computer equipment and software 33,823 27,633
table: Furniture and equipment 4,840 4,457
table: Total, at cost 71,807 58,683
table: Accumulated depreciation (35,330) (29,223)
table: Total, net $  36,477 $  29,460
question: Analyse this data from a financial earnings document. How much was the average depreciation expense over the 3 year period from 2017 to 2019?