At work part of my job is reporting security metrics along with my colleague, and sometimes we report things like the number of machines running a specific operating system. The problem we run into is that when it comes to operating system versions, OS X versions 10.1 and 10.10 are really not the same. We run into similar issues with versioning for other operating systems too, such as AIX.
To keep Excel from dropping those significant zeroes on your charts, highlight the column containing your version data and switch it from a numeric format to text format. Then switch to the tab that contains your chart, refresh the data, and your charts will show the zeroes properly.