From: Change in the prevalence asthma, rhinitis and respiratory symptom over a 20 year period: associations to year of birth, life style and sleep related symptoms
Respiratory symptoms
Smoking
BMI
Sleep related
1990–1994
21,595
14,780
6604
1867
1999–2001
16,049
15,930
15,762
2010–2012
13,093
12,738
12,930
12,811
≥ 2 surveys
17,711
13,117
12,504
11,338
All three surveys
11,269
10,858
3669
1143