def METHOD_NAME(previous, current, property_name):
    """
    PERF_100NSEC_TIMER
    https://technet.microsoft.com/en-us/library/cc728274(v=ws.10).aspx
    """
    n0 = previous[property_name]
    n1 = current[property_name]
    d0 = previous["Timestamp_Sys100NS"]
    d1 = current["Timestamp_Sys100NS"]
    if n0 is None or n1 is None:
        return
    return (n1 - n0) / (d1 - d0) * 100