If you've had traffic monitoring enabled and properly configured in DSLstats for some time, then that information is readily available from the Traffic graphs. But you can't get the information just by looking at the current telnet data (unless your usage is very low or you've very recently restarted the modem). The reason is that the total upstream and downstream traffic figures from the modem (shown in the Telnet Data --> Traffic page of DSLstats) are held in variables which wrap round to zero when they reach their maximum possible values (like an old fashioned car odometer).