The statistics of disk and traffic data usage and also the web statistics are calculated for every 24 hours. The statistics can be updated automatically and it can also be generated manually by using the command-line utility statistics. This utility can be run using the command plesk sbin and it is located at /usr/local/psa/admin/sbin.
For generating the web statistics for all domains, use the following command
plesk sbin statistics --generate-all-webstat