This small dataset, and corresponding figures, supports the main conclusions drawn in:
P. Cuffe, "Assortativity Anomalies in a Large Test System," in IEEE Transactions on Power Systems, vol. 31, no. 5, pp. 4169-4170, Sept. 2016. doi: 10.1109/TPWRS.2015.2499700
These metrics indicate that 'nesta_case9241_pegase.m' is an outlier in terms of network structure, and thus may not be representative of a realistic electrical transmission system.
Regarding the rich club coefficient, see:
V. Colizza, A. Flammini, M. A. Serrano, and A. Vespignani, “Detecting rich-club ordering in complex networks,” Nature Physics, vol. 2, no. 2, pp. 110–115, 2006.