My company is based in Japan, and we want to add a custom dropdown field for English ability for all contacts. (put simply, everyone would be rated as none, basic, low-intermediate, intermediate, high-intermediate, advanced, fluent or native)

The question I have is, how can I create this field and make it searchable so that I can return results of all people with intermediate or better English?

I was thinking that a way to do this would be to set a value from 0 to 8 for each level. (None = 0, Basic = 1, Low-Int = 2...Native = 8) I figured that would make it easy to search for an English level greater or equal to X.

That seems to make sense...but I can't figure out how to implement it in practice. Does anyone have any advice on how to set up custom fields to accomplish this?