Table 1. Demographic characteristics of the sample population during the study period .
| Demographic variables | 2006 | 2007 | 2008 | 2009 |
| N (%) | N (%) | N (%) | N (%) | |
| Gender | ||||
| Male | 599 (34.0) | 629 (36.2) | 591 (33.8) | 518 (33.2) |
| female | 1162 (66.0) | 1107 (63.8) | 1159 (66.2) | 1043 (66.8) |
| Age | ||||
| Mean (±SD) | 20.4 (± 2.6) | 20.2 (± 2.1) | 20.2 (± 1.9) | 20.1 (± 1.9) |
| Min | 15 | 16 | 17 | 15 |
| Max | 43 | 41 | 42 | 40 |
| Mode | 20 | 20 | 20 | 21 |
| Marital status | ||||
| Single | 1636 (93.2) | 1633 (94.1) | 1640 (93.7) | 1446 (93.5) |
| Married | 120 (6.8) | 103 (5.9) | 110 (6.3) | 101 (6.5) |
| Place of residence | ||||
| Home (with family) | 862 (49.1) | 772 (44.7) | 811 (46.5) | 706 (45.1) |
| Home (alone or with other single roommates)/ in dormtory | 892 (50.9) | 956 (55.3) | 933 (53.2) | 858 (54.9) |
| Field of study | ||||
| Medicine | 837 (47.6) | 738 (43.5) | 633 (36.3) | 408 (26.0) |
| Pharmacy | 257 (14.6) | 303 (17.9) | 300 (17.2) | 288 (18.4) |
| Dentistry | 191 (10.9) | 199 (11.7) | 206 (11.8) | 211 (13.5) |
| Nursing and midwifery | 172 (9.8) | 183 (10.8) | 224 (12.9) | 213 (13.6) |
| Health and hospital management | 111 (6.3) | 100 (5.9) | 86 (4.9) | 81 (5.2) |
| Others* | 192 (10.9) | 174 (10.3) | 294 (16.9) | 367 (23.4) |
| Year of study of the students | ||||
| First year | 590 (33.5) | 536 (30.9) | 536 (30.6) | 534 (34.1) |
| Second year | 476 (27.0) | 519 (29.9) | 471 (26.9) | 373 (23.8) |
| Third year | 299 (17.0) | 403 (23.2) | 497 (28.4) | 408 (23.0) |
| Fourth year | 397 (22.5) | 278 (16.0) | 246 (14.1) | 253 (16.1) |
*Includes bachelor degree in radiology, radiotherapy, speech therapy, physiotherapy, operating room technician, medical information, audiometry and nuclear medicine