Assume the following property and equipment footnote was obtained from the deere & company's 2016 10-k. property and depreciation a summary of property and equipment at october 31 follows: ($ millions) average useful lives (years) 2016 2015 equipment operations land $79 $75 buildings and building equipment 25 1,490 1,419 machinery and equipment 10 2,961 2,870 dies, patterns, tools, etc 7 1,039 987 all other 5 589 571 construction in progress 232 156 total at cost 6,390 6,078 less accumulated depreciation 4,113 3,966 total $2,277 $2,112 during 2016, the company reported $636.5 million of depreciation expense (this expense also includes amortization expense relating to computer software that is included with property and equipment). estimate the percent used up of deere's depreciable assets.