agents who historically booked the most travel to the PRC ?

Does " agents who historically booked the most travel to the PRC " mean "travel agents that, historically speaking, have had (served) the largest numbers of customers (travellers to the PRC) "?

Context:

Travel Agent Attitudes Toward China After Tiananmen Square
Wesley S. Roehl
Department of Tourism and Convention Administration, William F. Harrah College of Hotel Administration, University of Nevada, Las Vegas
Abstract
This study examines travel agents' attitudes toward the People's Republic of China (PRC) following the events of Summer 1989. Travel agents opposed both a government ban on travel and an industry-organized boycott of travel to the PRC, and emphasized letting the public make an informed choice concerning travel to China. The opinion of these agents was that it will take at least until the period of Fall 1990 to Fall 1991 for travel to China to return to pre-June 1989 levels. Recovery may be slower, however, because agents who historically booked the most travel to the PRC expressed the most hostile attitudes toward the PRC. '

More:

http://jtr.sagepub.com/content/29/2/16.short