Diagram of the circular (m_C) and linear (m_L) fractional polarizations for the whole sample. The fractional polarization m_C and m_L are determined for the Stokes V and p peaks, respectively. The sources with a polarized flux density lower than 3σ detection level are assumed to have a fractional polarization equal to zero. The points of |m_C| > 20% or/and m_L > 10% are labelled with the names of the sources. The thick dashed line defines the relation between the fractional polarizations of the form m_C = 2.7m_L + 1.5.