@Override
		public String toString() {
			return super.toString() +
				"+---------------------------------------------------------------------------+\n" +
				"|  Population statistics                                                    |\n" +
				"+---------------------------------------------------------------------------+\n" +
				format(cpattern, "Age:", p(_age)) +
				format(cpattern, "Fitness", "") +
				format(spattern, "min =", _fitness.min()) +
				format(spattern, "max =", _fitness.max()) +
				"+---------------------------------------------------------------------------+";
		}
Return the minimal and maximal fitness.

@return minimal and maximal fitness
jenetics/src/main/java/io/jenetics/engine/EvolutionStatistics.java