Figure 3From: West Sweden Asthma Study: Prevalence trends over the last 18 years argues no recent increase in asthma Comparison of the prevalence of respiratory symptoms using identical questions in the ECRHS Study (1990) and in the current study (2008) among 20-44 year old subjects living in the area of Hisingen, Gothenburg (* p < 0.05, ** p < 0.01, ***p < 0.001).Back to article page