fix --stat output

    mean_power = running_mean(power_from_energy, 10)

    if 'stat' in opt:

        mean_voltage = np.mean(data[:, 2])

        mean_current = np.mean(data[:, 1])

        mean_power = np.mean(data[:, 1] * data[:, 2])

        mean_voltage = np.mean(data[:, 2] * 1e-3)

        mean_current = np.mean(data[:, 1] * 1e-9)

        mean_power = np.mean(data[:, 1] * data[:, 2] * 1e-12)

        print('Mean voltage: {:.2f} V       : {:.9f}'.format(mean_voltage, mean_voltage))

        print('Mean current: {:.0f} µA       : {:.9f}'.format(mean_current * 1e6, mean_current))

        print('Mean power: {:.0f} µW       : {:.9f}'.format(mean_power * 1e6, mean_power))

        print('Total energy: {:f} J       : {:.9f}'.format(m_energy_nj, m_energy_nj))

        print('Total energy: {:f} J       : {:.9f}'.format(m_energy_nj * 1e-9, m_energy_nj * 1e-9))

    if 'plot' in opt:

        # nA * mV = pW