@Override
		public int compare(VirusStats v1, VirusStats v2) {
			Long extinct1 = extinction.get(v1.getVirus());
			Long extinct2 = extinction.get(v2.getVirus());
			if (extinct1 == null && extinct2 == null)
				return 0;
			else if (extinct1 == null)
				return -1;
			else if (extinct2 == null)
				return 1;
			return -extinct1.compareTo(extinct2);
		}