Add a new column to your task report, any column will do, then using text mode, replace the text with the below code:
aggregator.function=AVG
aggregator.valueexpression=WEEKDAYDIFF({entryDate},{actualCompletionDate})
aggregator.valueformat=val
displayname=Work Days to Complete
textmode=true
valueexpression=WEEKDAYDIFF({entryDate},{actualCompletionDate})
valueformat=
The average will be calculated by grouping and appear in the grouping row; so if you group by user, it will show you each user's average; if you group by team it will show you each team's average, etc. credit to Narayan Raum for including that code in his most excellent TEXT MODE LIBRARY document. Bill William English
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