If you want to see which nationality travels to you most often and spends the most with you, use the report Revenues from accommodation by nationality.
In the report you can filter by period and for individual countries you will be shown exactly how many people of a given nationality you have, the number of bednights, roomnights, revenue and on average the price per night.
This is a live report, so you can add information to the reservation retrospectively.
The data in the report are loaded by filling in the nationality in the reservation. If the nationality is not filled in, it will appear in the report as three dots. States are loaded regardless of whether or not the reservation is in checkin.