Departures magazine circulation:
December 2006 (page 3) shows 17,875 Personal + 5,630 Business = 23,505 USA Centurion cardholders.
http://www.departures.com/mediakit/d...s/DEP_1206.pdf
June 2007 (page 3) shows 19,523 Personal + 6,752 Business = 26,275 USA Centurion cardholders
http://www.departures.com/mediakit/d...P_BPA_0607.pdf
December 2007 data is not yet online. Corresponding Platinum cardholder data is also included. Suffice it to say there is no exclusivity with well over 1 million accounts.
This indicates 2,770 (11.7%) additional Centurion accounts created in six months. Put another way, American Express sold over 15 Centurion memberships per calendar day. Ignoring initiation fees, that's $6.925 million in incremental annual fee revenue.