The ratio of number of residents in zip code 93405 to the number of sex offenders is 2,782 to 1. The number of registered sex offenders compared to the number of residents in this zip code is a lot smaller than the state average. Back to: San Luis Obispo, CA, All cities.Back to the top. Home price trends powered by Onboard Informatics. © 2012 Onboard Informatics.he number of registered sex offenders compared to the number of residents in this zip code is a lot smaller than the state average. Back to: San Luis Obispo, CA, All cities. Back to the top. Home price trends powered by Onboard Informatics. © 2012 Onboard Informatics.