def cpu_percent(interval=0.01):
    """Return the current system-wide CPU utilization as a percentage.
    Interval
    """
    t1 = cpu_times()
    t1_all = sum(t1)
    t1_busy = t1_all - t1.idle

    time.sleep(interval)

    t2 = cpu_times()
    t2_all = sum(t2)
    t2_busy = t2_all - t2.idle

    busy_delta = t2_busy - t1_busy
    difference = t2_all - t1_all
    try:
        busy_perc = (busy_delta / difference) * 100
        if busy_perc < 0.0:
           raise ZeroDivisionError
    except ZeroDivisionError:
        raise ValueError("inverval too low")
    else:
        return float(busy_perc)