There is no easy way to include the information you are after in a report. TblAssets.Uptime only stores the uptime since the last reboot. There are uptime events (reboots, shutdowns...) stored in tblUptime as well, but there is no easy way to calculate uptime from this for a given time period, using SQL reports. We posted a sample query that summarizes uptime
here, but this query only works in the SQL Server database server, will take a long time to run and is not easily customizable.