That depends on your settings, in particular on what adapters are selected for monitoring and whether the "Ignore local traffic within the LAN" option is enabled.
If Ignore local traffic within the LAN is ticked, check per application reports under Usage Reports - Applications. It's quite possible that you will see a network filtering product like an antivirus shown in the list. In many cases an antivirus or other security software would intercept all connections from web-browsers, which may be recorded twice (once for a web-browser and then again for the antivirus). If this is the case, try installing the so-called WFP driver as described in this article.
If Ignore local traffic within the LAN is NOT ticked, make sure you are monitoring one network interface instead of all interfaces. Open the NetWorx settings and choose one specific network interface to monitor. When NetWorx is set to monitor all traffic on all network interfaces (possibly adding local traffic or multiple adapters, including virtual and dial-up ones), it sums it all up, which results in incorrect, very high readings.
You can press CTRL+O in the Settings window to access the hidden Options. In those Options is a line called "Useage adjustment (factor)". So if the reported value is always wrong by the same factor, you can enter a correction factor in here.