How to analyze which site has most numbers
The most obvious way of visualizing this is to have the number of computers on the Y-axis and the size of the dots representing the percentages. The categories (or sites in your case) can be represented on the X-axis. The image below shows an example where the Y-axis represents a continuous value (can be mapped to number of computers in your case), the X-axis represents a discrete value (can be mapped to sites in your case), and the size of the dots represents another attribute (like percentage in your case). I have used the R package ggplot2 for this.