The way to customize the report to show just the customers and not the jobs would be:
1. Run the Customer contact list report.
2. Click Customize in the upper left of the report.
3. Under the Filters tab click Customer under the Fitlers list.
4. In the drop down next to that list, select the option Multiple customers/jobs.
5. A box should open up and on the right should be the list of your customers and jobs.

This is the manual process. In this list you can go through and select only your customers and not the jobs. The ones selected will have a check mark placed next to the name. Once you have selected just the customers click OK in that box and then OK again in the Modify report box. This should update the report to show just the customers and not the jobs associated with them. Then you can export it to excel to get the correct count.