1. Department of Otorhinolaryngology; Head and Neck Surgery, Charité-University Hospital, Campus Benjamin Franklin; Berlin Germany
2. Private Statistical Office; Berlin Germany
3. Berlin School of Public Health; Berlin Germany
4. Department of Otorhinolaryngology, Head and Neck Surgery; Charité-University Hospital, Campus Virchow-Klinikum; Berlin Germany
5. Department of Otorhinolaryngology, Head and Neck Surgery; Klinikum Bielefeld; Bielefeld Germany