Distribution of percent densities among the 695 study subjects of the DIOS-Study 2006–2008 according to age group. Box width varies with age group size. Whiskers indicate observations between the lower and upper fence [i.e. 1.5*interquartile range (IQR) below 25th percentile and 1.5*IQR above 75th percentile]. Plus symbols indicate observations outside the fences. Filled squares indicate mean percent density values. Horizontal lines within the boxes indicate the median percent density values.