Figure 2.

Mean population density in census block groups with zero to three WNV human disease cases (2002–2006). On the x-axis is the mean population density (persons/ha²) for census block groups calculated according to the number of WNV disease cases (i.e. 0, 1, 2, or 3 cases). The number of census blocks which had that number of cases is shown above the point in the graph.