The average proportions (%) of working hour characteristics during past 91 days in 2008–2015
| Percentages of… | 2008 | 2012 | 2015 | |||
| N | Mean (SD) | N | Mean (SD) | N | Mean (SD) | |
| >40 hour work weeks of all work weeks | 920 | 23.6 (17.2) | 918 | 26.6 (22.8) | 920 | 22.7 (19.6) |
| >48 hour work weeks of all work weeks | 920 | 3.1 (6.5) | 918 | 4.0 (10.0) | 920 | 3.1 (6.7) |
| Quick returns (<11 hour) of all shift intervals <48 hour | 920 | 13.5 (14.8) | 920 | 11.2 (13.6) | 920 | 9.5 (12.6) |
| Single days off of all day off-periods | 730 | 13.3 (9.7) | 667 | 7.9 (15.1) | 530 | 19.1 (11.4) |
| Evening shifts of all shifts | 920 | 18.8 (16.8) | 920 | 17.5 (17.3) | 920 | 17.0 (18.3) |
| Night shifts of all shifts | 920 | 8.5 (13.9) | 920 | 7.9 (15.1) | 920 | 7.5 (14.5) |
| Weekend work of all weekends | 920 | 27.7 (25.4) | 920 | 26.2 (25.6) | 920 | 21.8 (22.9) |