Job and Resume Categories

Recently we added categories to PostJobFree.com
So now you can browse jobs or resumes.
For example, take a look at the most popular sales category.

How do we define list of categories?
We took the most popular search query and used them as categories.

How do we rank categories?
1) The more people search for category -- the higher rank of this category is.
2) The more jobs (or resumes) category contain -- the lower rank of this category is.
3) Rank of job category may be quite different from the rank of resume category.
For example, "mail clerk" job category has high rating: job seekers search for it, and there are not so many jobs in "mail clerk" category.
At the same time "mail clerk" resume category has low rating: few recruiters searching for it, and there are lots of "mail clerk" resumes.