If new-development condos were included, condo sales probably started outnumbering SFD sales about 9 or 10 years ago. Looking just at sales reported to MLS, that switch occurred in 2012. This trend will only continue to accelerate with all the new condo construction occurring in the city. There are few counties in the country where condo sales outnumber house sales.
TIC and 2-4 unit building unit sales have fallen dramatically since their peaks. As time goes on, there are simply fewer and fewer 2-4 unit buildings existing in the city that haven’t been turned into condos and TICs. TICs have been affected by a number of issues: conversions into condos, new restrictions and costs on tenant evictions, changes in lending terms, and so on. The general decline of 2-4 unit buildings is irreversible since hardly anyone is building more of them. The inventory and sales volume of TICs may change.
Online, this report can be found here: http://www.paragon-re.com/SF_Home_Sales_by_Property_Type
I also updated this chart on the sale of 2 BR condos. Note it is for non-distressed condos with sales prices up to $2m. Every time one tweaks the parameters or time frame, the results will be different.