(Coincidentally) I've been doing some experiments with AI::Genetic::Pro. Some sample output showing the best, average and min fitness of each generation.

2016-08-19 21:42:34,960|GEN ==> 8, 62.000000, 18.000000, -216.900000
2016-08-19 21:43:11,714|GEN ==> 9, 62.000000, 19.000000, -28.340000
2016-08-19 21:43:49,558|GEN ==> 10, 62.000000, 26.000000, -63.970000
2016-08-19 21:44:26,772|GEN ==> 11, 62.000000, 29.000000, -47.570000
2016-08-19 21:45:03,968|GEN ==> 12, 62.000000, 37.000000, -32.000000
2016-08-19 21:45:41,308|GEN ==> 13, 62.000000, 51.000000, -34.000000
2016-08-19 21:46:18,268|GEN ==> 14, 62.000000, 56.000000, -34.750000
2016-08-19 21:46:55,695|GEN ==> 15, 62.000000, 58.000000, -2.000000
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The difference between the best and average fitness shows the GA is converging, and it may be a good time to stop.