Client utilization in the European situation is more difficult to analyze. Studies on sites in Frankfurt and Zurich found that clients used facilities 5 times a week and in Rotterdam 6 times a week and twice in the previous 24 hours. A study of clients in Frankfurt in 1997 found that 63% claimed to be daily visitors, while in another surveyed non-random sample from 18 German consumption rooms, 84% claimed use of the facility at least once weekly, with 51% claiming at least once per day utilization.