Problem of lack in results in reports, can u help me?

Hello!

I'm creating a simple report for extract all the contacts:

- No filter added

- Columns:

    - Account Name

    - Billing city (may be empty)

    - First name

    - Last name

    - Title

    - Office phone

    - Mobile

    - Email address

When I run the report, I obtain 1200 results, what it's insignificant. I look for some of the key accounts where I have lots of contacts and most of these accounts don't appear. There a big lack of results and no filter has been added.

Thanks.

Best regards!