Help to design relations between some 5 tables with possible many-to-many relations

Hi,

I have the following tables: *reports*, *standards*, *elements*, *tables*,
*items*.
* One *report* has many *standards*.
* One *standard* has many *elements*.
* One *element* has many *tables*.
* One *table* has many *items*.

*Reports* are generated yearly and current year might have exactly the same
*standards* as last year but not necessarily. Maybe, the current year
*report* includes part of last year's report *standards* and also includes
new *standards*. Or maybe, the current year report includes only a subset
of last year *reports* *standards*. Or maybe, the current report has a
totally new set of standards.The same behavior is true between *standards*
and *elements*, between *elements* and *tables* and between *tables* and
*items*. I see that many-to-many relations exist between all of the tables
but I am not able to clearly visualize.

I am a bit confused about how to design this part of my DB. I hope my
explanation is clear enough. I will very much appreciate your feedback.

Respectfully,
Jorge Maldonado