IdInfoComp : Integer Not Null (PK)
 IdDefinition : Integer Not Null (FK)
 IdObject : Integer Not Null (FK)
 Value : NVarChar(Max) Not Null

SELECT AVG(Value) FROM InfoComp
 Result : 8

(Size(IdInfoComp) + Size(IdDefinition) + Size(IdObject) + AVG Size(Value)) * Rows count
 ( 4 + 4 + 4 + ((8 * 2) + 2)) * NbRows