How many snowbirds does San Diego get around this time of year?

Arizona gets a lot, Florida gets a lot, but it seems that SoCal gets some as well. I thought that since SoCal was so expensive to live in nowadays, snowbirds would drift more towards Arizona. I'm looking at the amount of business retail stores receive now in San Diego, but if those numbers are heavily inflated by the number of snowbirds there, then that means business in the off season is going to be slower.

Does it seem like there's less traffic in San Diego around the spring/summer seasons because snowbirds go back home, or is it pretty consistent with the winter?

Thank-you for your time!