What is the actual average cost for single coverage dental insurance and vision insurance to an employer?

I live in Iowa and just wanted some basic figures on what my employer would spend on these types of coverages for me, a single 23 year old male with no children? I realize it depends on the company and there are ranges depending on coverage but just wanted a basic idea.
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Dental- About $20-$30 per month, but remember it is highly dependent upon both the items covered and the maximum annual payment limit. Dental insurance is much different than medical/Dr coverage and considered by many as not a good use of your money. For example many policies won't cover the really expensive items like braces and will have an annual payment cap of $1000. After you have paid $300-$500 annually into it, that max does not leave you much room to have any real coverage. Vision - is much the same issue in that both benefits coverage and little risk coverage for the cost.
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