Whither the single family home (in Pittsburgh)?

Just a curious time series if you have not seen it. Take a look at the time series for building permits for single unit homes across the Pittsburgh MSA.

Source: https://fred.stlouisfed.org/series/PITT342BP1FH

To be clear, this is for building permits issued only for single unit homes, not building permits overall. Still, something seemingly fell off the cliff for Pittsburgh at the end 2014, and has not come back. The lastest month here (August 2017) is showing 94 total single family homes being planned across the 2.35 million person Pittsburgh MSA. That works out to 4 per 100,000 in population.

It is a remarkably low number not just compared to Pittsburgh's past, but compared to other regions.  Without getting into a full benchmarking exercise, the 2.1 million person Cleveland MSA is showing 252 single unit building permits for the same month. That comes out to over 12 per 100,000 population. Both Pittsburgh and Cleveland are well below the national rate, which is still rebounding from the Great Recession. Nationally the 819K building permits in August work out to just over 250 per 100K population.

That's all I have. If anyone has a clear explanation for the Pittsburgh drop right at the beginning of 2015, either in the local housing market, or if there is something else going on in the data, I'd love to hear about it.