Quantification of arm/interarm contrast for large-scale (thick lines) and small-scale (thin lines) fields for material arms (red dashed lines) and interarm regions (blue solid lines), for models 75, 76, 77 (from top to bottom). The peak in small-scale field at approximate time 12 Gyr as well as other details of small-scale magnetic field distribution are probably caused by the chance coincidence of an injection event with the analysed snapshot of the field.