| Year | 2001 | 2002 | 2003 | 2004 | 
    
      | Total Registrants | 315 | 281 | 406 | 296 | 
    
      | Tech Plenary Day Registrants | 253 | 239 | 334 | 267 | 
    
      | Groups Meeting | 19 | 21 | 30 | 28 | 
  
Not counted -- but important -- are formal cross-Group meetings and
many informal discussions at the coffee breaks, etc.