SOA - Average size of composite instance in your DB?

I'm trying to work out a retention policy and I'm having a hard time figuring out how much space a average composite instance takes up in our DB. Was wondering if anyone had any pointers?

Thanks in advance,

Anthony

Fusion Middleware 11.1.1.5
Linux x86-64
DB 10.2.0.4
Avergage instances/day = 1000
No regulatory requirements

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