After reviewing the above listed site I happened to find a slight discrepency in the 19,906 number. The regional list for San Diego is somewhat misleading, North County Inland actually includes the following areas:

Sun City
Hemet
Murrieta
Perris
Riverside
Winchester
Lake Elsinore
Menefee
Temecula
Wildomar

All of which I believe are in Riverside County not San Diego County. Murreita is actually listed twice with the same number which leads me to believe that this type of duplication might be present elsewhere in the San Diego numbers resulting in an over inflated number for the other regions. Anyhow when the Riverside numbers are removed the actual number is more like 19,171.