private static void listCustomers(TravelAgent agent) {
		System.out.println("Listing customers...");
		System.out.println("ID: \t Name: \t Child Seats: \t Adult Seats: \t Cost:");
		// for every element of the list print them out here
		for (Customer c: agent.customerList){
			System.out.println(c.getId() + "\t" + c.getName() + "\t" + c.getChildSeats() + "\t\t" + c.getAdultSeats() + "\t\t" + c.getCost());
		}
		listMenu(agent);
	}