Figure 2. Incidence of pyogenic liver abscess in Taiwan, showing a steady increase from 1996 to 2004. The incidence is expressed as the number of new cases reported from the population (the National Health Insurance database) per year. A) The linear increase of the primary incidence data (raw incidence) with the year can be described by this formula: incidence (×1/100,000) = 0.860 × year – 1704.66 (r = 0.978, p<0.001). B) The linear increase of the standardized incidence data (the incidence normalized according to the age distribution of the population) with the year can be described by this formula: incidence (×1/100,000) = 0.512 × year – 1010.68 (r = 0.923, p<0.001). r, Pearson correlation coefficient.