Figure. A) Number of norovirus outbreaks reported per month in the Netherlands, 1994–2005. B) Total no. of outbreaks per season and fraction of GGII.4 outbreaks reported in the Netherlands. Total no. is indicated by the solid line, no. of GGII.4 outbreaks by the dotted line (values on left y-axis), bars indicate percentage of GGII.4 outbreaks of the total no. (values on right y-axis), and arrows indicate epidemic seasons. Seasons run from July through June. C) Total no. of genotypes (Gts) circulating per season. Shading of the bar indicates the percentage of GGII.4, ranging from white (0%–20%), in steps of 20%, to black (80%–100%).