This is a great point. The author's last graph tries to make the point that that the fraction of income taken from tenants has outpaced tenant wage growth over

This is a great point. The author's last graph tries to make the point that that the fraction of income taken from tenants has outpaced tenant wage growth over a period of decades. In present day SV (especially SF), most landlords will require tenants spend no more than 30% of their income on rent as part of the application process-- it's a somewhat fixed rule-of-thumb. As rents have risen, a lot of tenants in non-rent-controlled housing have been effectively priced out and displaced elsewhere. So it's actually not so easy to demonstrate that landlords have been taking a larger fraction of tenant income; one must adjust for the fact that greedy landlords will also drive away poorer tenants. Simpson's Paradox at work.