I sorted the data by which occupation marries within the same occupation the most:<p><pre><code>     13.9%    Physicians and Surgeons
     10.7%    Textile Winding, Twisting, and Drawing Out Machine Setters, Operators, and Tenders
     10.1%    none
      9.7%    Farmers, Ranchers, and Other Agricultural Managers
      9.7%    Lawyers, and judges, magistrates, and other judicial workers
      9.5%    Miscellaneous Personal Appearance Workers
      9.3%    Veterinarians
      8.8%    Dentists
      8.5%    Miscellaneous agricultural workers including animal breeders
      8.4%    Postsecondary Teachers
      7.6%    Software Developers, Applications and Systems Software
      7.6%    Health Diagnosing and Treating Practitioners, All Other
      7.5%    Optometrists
      7.3%    Chiropractors
      7.2%    Pharmacists
      6.7%    Elementary and Middle School Teachers
      6.4%    Food Service Managers
      6.2%    Agricultural and Food Scientists
      6.1%    Physical Therapists
      6.1%    Gaming Services Workers
      6.0%    Upholsterers
      5.9%    Communications Equipment Operators, All Other
      5.8%    Air Traffic Controllers and Airfield Operations Specialists
      5.8%    Physical Scientists, All Other
      5.8%    Nurse Anesthetists
      5.5%    Chief executives and legislators
      5.5%    Real Estate Brokers and Sales Agents
      5.4%    Clergy
      5.2%    Marine Engineers and Naval Architects
      5.0%    Psychologists
      4.9%    Lodging Managers
      4.8%    First-Line Supervisors of Retail Sales Workers
      4.7%    Miscellaneous Managers, Including Funeral Service Managers and Postmasters and Mail Superintendents
      4.7%    Medical Scientists, and Life Scientists, All Other
      4.6%    Secondary School Teachers
      4.0%    Textile Knitting and Weaving Machine Setters, Operators, and Tenders
      4.0%    Podiatrists
      4.0%    News Analysts, Reporters and Correspondents
      4.0%    Sewing Machine Operators
      3.9%    Bailiffs, Correctional Officers, and Jailers
      3.9%    First-Line Supervisors of Personal Service Workers
      3.8%    Tailors, Dressmakers, and Sewers
      3.8%    Economists
      3.8%    Musicians, Singers, and Related Workers
      3.8%    Environmental Scientists and Geoscientists
      3.8%    Property, Real Estate, and Community Association Managers
      3.7%    Insurance Sales Agents
      3.5%    Agricultural Inspectors
      3.3%    Butchers and Other Meat, Poultry, and Fish Processing Workers
      3.2%    Morticians, Undertakers, and Funeral Directors</code></pre>