Characteristics of the study population
| Study year (wave) | 2009 | 2011 | 2013 | 2015 | 2017 | 2019 |
| All respondents | n=1003 | n=1005 | n=1002 | n=1004 | n=1042 | n=1011 |
| Male | ||||||
| n | 478 | 479 | 477 | 481 | 499 | 484 |
| % | 47.7 (44.6–50.8) | 47.7 (44.6–50.8) | 47.6 (44.5–50.7) | 47.9 (44.8–51.0) | 47.9 (44.9–50.9) | 47.9 (44.8–51.0) |
| Female | ||||||
| n | 525 | 526 | 525 | 523 | 543 | 527 |
| % | 52.3 (49.3–55.4) | 52.3 (49.3–55.4) | 52.4 (49.3–55.5) | 52.1 (49.0–55.2) | 52.1 (49.1–55.1) | 52.1 (49.1–55.2) |
| Non-smokers | ||||||
| Overall | ||||||
| n | 710 | 694 | 733 | 763 | 789 | 798 |
| % | 70.8 (67.9–73.5) | 69.1 (66.1–71.8) | 73.2 (70.3–75.8) | 76.0 (73.3–78.5) | 75.7 (73.0–78.2) | 79.0 (76.3–81.3) |
| Male | ||||||
| n | 311 | 291 | 329 | 333 | 355 | 366 |
| % | 65.1 (60.7–69.2) | 60.8 (56.3–65.0) | 69.0 (64.7–73.0) | 69.2 (65.0–73.2) | 71.1 (67.0–74.9) | 75.6 (71.6–79.2) |
| Female | ||||||
| n | 399 | 403 | 404 | 430 | 434 | 432 |
| % | 76.0 (72.2–79.5) | 76.6 (72.8–80.0) | 77.0 (73.2–80.4) | 82.2 (78.7–85.3) | 79.9 (76.4–83.1) | 82.0 (78.5–85.0) |