How can I see the total quantity of parts used in my assembly in SolidWorks?

I am not too sure if you have found it. But if you click on the Evaluate Tab and then click on Assembly Visualization, it should give you the Quantities of all of your parts. It can also be found under Tools - Assembly Visualization.

In Solidworks, select Tools - AssemblyXpert

This will give you what you are looking for.

Try this it might work out
Please go to tab Evaluate -> Performance Evaluation and the second option in large assembly Mode in that they say how many components are there

I'm afraid that I wrote my question in wrong way.
I mean i have assembly with meny subassemblies (with screws mirrors of it and patterns of parts).
I do not wanna to count them all in the main assembly tree by cliking on the + in the each subassembly and its mirrors and patterns operations.... it takes long time and i will make mistake for sure.
I thought that there is some option to do that....

Yes @Ryan this is good way obtain total quantity of separate parts.Thanks.
It can be useful when i do not have 2d drawing of assembly.

Becouse in 2d drawings i could just look in the bill of materials table.

I have only been using Solidworks for almost a year now and I just found that option/command. If you click on Assembly Visualization, there is an options that you can select to have all parts. Those options can be found beside the "File Name" when you have the Assembly Visualization open. I believe you have the choice of "Flat/Nested view", and "Grouped/UnGrouped". I know that this has just helped me out for my 3d models. I hope this can help in some way.