What is causing the astronomical increase in rents in San Diego?

The rent for my old crappy apartment was originally $1,900 for a 2BR 2B. It is now $3,200.

My current apartment was $2,700. It is now listing for $4,000.

$4,000 used to be able to give you a brand new luxury apartment in La Jolla.

This all occurred in the past year, maybe even the past two to three months.

What has changed in San Diego? Why are rent prices so expensive now?