Creo que tendrás que contar los registros por cada tabla, prueba este procedure.
Código SQL
[-]
CREATE OR ALTER PROCEDURE ContarRegistrosTablas RETURNS (
TABLA VARCHAR(31),
CANTIDAD INTEGER
)
AS
BEGIN
For Select RDB$Relation_Name From RDB$Relations
Where (RDB$System_Flag = 0) And (RDB$View_BLR Is Null)
Order By RDB$Relation_Name Into :Tabla Do
Begin
Execute Statement 'Select Count (*) From ' || :Tabla Into :Cantidad;
Suspend;
End
End