how to calculate the total system load in a script based upon wmic outputs?

Question

when i use the below mentioned command line on Windows 7 or similar in a cmd.exe shell on a laptop i get something like this:

    C:\>wmic cpu get LoadPercentage /value | find "LoadPercentage"
    LoadPercentage=15

doing the very same on a server class machine gives me something like this:

    C:\>wmic cpu get LoadPercentage /value | find "LoadPercentage"
    LoadPercentage=48
    LoadPercentage=50

-- a bit of a backgrounder for why the outputs might be different...

doing a systeminfo on the laptop (German language Windows) looks like this:

    C:\>systeminfo
    [...]
    Prozessor(en): 1 Prozessor(en) installiert.
                   [01]: Intel64 Family 6 Model 30 Stepping 5 GenuineIntel ~1734 MHz

doing the same on the server looks like this:

    C:\>systeminfo
    [...]
    Processor(s): 2 Processor(s) Installed.
                  [01]: Intel64 Family 6 Model 62 Stepping 4 GenuineIntel ~2600 Mhz
                  [02]: Intel64 Family 6 Model 62 Stepping 4 GenuineIntel ~2600 Mhz

-- backgrounder end.

my question is now:

how can i get the total sum of system load on the shell all the time? (instead of this per-processor listing as provided in the server case)

maybe some cmd.exe magic is possible or maybe something else than 'wmic' will serve me better in that case. i probably want to stick with standard programs and tools instead of adding third party software. thus the solution hopefully would run everywhere.