Statistics of the period ratios of both inner pairs. Upper plot: blue columns showing all 2+2 quadruples, green data showing the other non-eclipsing 2+2 systems from the MSC catalogue, red data are the unconfirmed systems detected but still not published yet, and, finally, the magenta data are our new seven systems presented in the current paper. Middle plot: only the systems with temperatures below 7000 K. Bottom plot: only the early-type systems with T_eff > 7000 K.