There are currently no data sources known which report these credentials by county. Several national organizations have called for such a data bank, but as of now none exists. If a community is interested in providing such data as a supplement, it is suggested that contact with organizations which issue occupational credentials (technical schools, community colleges, etc.) and/or employers and trade unions which recognize the credentials be engaged to provide any data they may have. All data must be sourced in your application and calculations shown.
Community surveys may also be another possible means of collecting such data, depending on how the data is collected and analyzed.