NSGA-II, η = 20, 1000 generations: 28 solutions, 28 feasible, IGD+ 0.0511, hypervolume 0.6538
NSGA-II, η = 5, 1000 generations: 300 solutions, 300 feasible, IGD+ 0.0008, hypervolume 0.7202
the whole front: hypervolume 0.7211
