Ok and have you been able to find out what is running at the times when you see growth? Is it index maintenance?

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What is running at 20:00 on a Monday? It looks like that might be the culprit and don't shrink your database until you understand what is causing it to grow...

Your 1st query uses 2015/09/30 in the where clause and your 2nd has no mention of 2015/09/30 so 81 records for 2015/09/17 is probably correct.

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Also how much memory does your server have? What is your max server memory set to? Is it solely used as a database server?

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What maintenance do regularly perform on your databases (Index maintenance etc.) and how often?

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Do you have good backups including transaction logs?

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