What do you mean by concurrent ?
Are you looking for number of connection per seconds, active connections, packet per second or bytes/second ?
http://www.cisco.com/en/US/products/hw/contnetw/ps789/products_data_sheet09186a00800921b1.html
This is the official info, and it talks only about 5.0Gbps throughput.
For more information you should contact your local reseller or Cisco representative.
Regards,
Gilles.