Table 1 Characteristics of the sample and measures of success in telephone sampling
2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | |
|---|---|---|---|---|---|---|---|---|---|
% or mean (±SD) | |||||||||
Final sample (n) | 54,369 | 54,251 | 54,353 | 54,367 | 54,339 | 54,144 | 45,448 | 52,929 | 40,853 |
Response rate (%)a | 71.1 | 71.5 | 74.6 | 76.5 | 76.4 | 64.9 | 64.8 | 71.5 | 65.2 |
Refusals (%) | 9.1 | 7.7 | 5.8 | 3.0 | 2.3 | 2.2 | 5.9 | 3.9 | 3.9 |
Women (%) | 53.9 | 53.8 | 53.9 | 53.9 | 53.9 | 53.9 | 53.9 | 53.9 | 53.9 |
Ageb | 42.1 (16.5) | 42.3 (16.2) | 43.2 (16.5) | 43.6 (16.5) | 44.2 (16.7) | 45.1 (16.9) | 46.2 (17.2) | 47.9 (17.6) | 48.3 (17.6) |
Age strata (%), years | |||||||||
18–24 | 18.9 | 18.2 | 17.9 | 17.2 | 17.1 | 16.7 | 16.4 | 15.9 | 15.6 |
24–34 | 25.4 | 25.4 | 25.4 | 25.5 | 25.4 | 25.4 | 25.3 | 25.3 | 25.3 |
35–44 | 20.6 | 20.5 | 20.4 | 20.3 | 20.1 | 20.0 | 19.9 | 19.7 | 19.6 |
45–54 | 15.8 | 15.9 | 16.1 | 16.3 | 16.4 | 16.6 | 16.8 | 16.9 | 17.1 |
55–64 | 10.0 | 10.2 | 10.4 | 10.7 | 10.9 | 11.1 | 11.4 | 11.6 | 11.8 |
≥65 | 9.4 | 9.8 | 9.8 | 10.0 | 10.1 | 10.2 | 10.4 | 10.5 | 10.6 |
Education, yearsb | 10.1 (4.5) | 11.0 (5.2) | 10.9 (4.9) | 11.2 (5.0) | 11.2 (5.0) | 10.8 (4.9) | 11.1 (5.0) | 11.2 (5.0) | 11.1 (5.1) |
Educational attainment (%), years | |||||||||
0–8 | 45.5 | 45.0 | 43.7 | 42.0 | 40.6 | 38.8 | 36.8 | 36.6 | 35.9 |
9–11 | 33.3 | 35.1 | 34.7 | 35.8 | 35.8 | 36.7 | 38.5 | 37.5 | 38.1 |
≥12 | 21.2 | 19.8 | 21.6 | 22.2 | 23.5 | 24.5 | 24.7 | 25.9 | 25.9 |
BMI (kg/m2)b | 24.9 (4.5) | 25.0 (4.6) | 25.2 (4.6) | 25.4 (4.7) | 25.6 (4.8) | 25.8 (4.9) | 25.9 (4.9) | 26.0 (4.9) | 26.2 (4.9) |
BMI categories (%) | |||||||||
BMI < 25 kg/m2 | 57.3 | 56.7 | 55.1 | 54.0 | 51.8 | 50.9 | 49.0 | 49.2 | 47.5 |
25 kg/m2 ≤ BMI < 30 kg/m2 | 30.8 | 30.0 | 31.2 | 31.6 | 33.1 | 33.3 | 33.6 | 33.2 | 34.6 |
≥30 kg/m2 | 11.9 | 13.3 | 13.7 | 14.3 | 15.1 | 15.8 | 17.4 | 17.5 | 17.9 |