On page 24 of the report from the Council of Economic Advisers to the President, titled Occupational Licensing: A Framework for Policymakers, there's a picture, and a table, of a hall of shame. Three states that license 30%, or more of their workforces. They are Washington (30.5%), Nevada (30.7%) and the socialist republic of Iowa (33.3%!).
The result is NOT driven by the occupational mix of these states. Iowa is an agricultural state and Washington has a thriving tech sector (led by Microsoft) and also builds a lot of airplanes. In addition, there is a second of group of states that ought to be shamed (or shunned) because of the difficulty of qualifying for an occupational license.
That group of Malignant Seven is led by Hawaii, where it takes 724 days to accumulate the experience and/or training for an average occupational license. Not far behind is Arkansas (689 days). Florida and Nevada both require over 600 days on average, while Arizona is nearly as bad at 599. California (549)and Oregon (568) both require over 500.
That's if you can get the bureaucracy to process your application.