San Francisco remains the nation's top tech hub, drawing young and highly educated workers, according to a new ranking by CBRE Group. Affordability concerns, however, are forcing companies to look elsewhere.

The Bay Area, Washington, DC, and Seattle took the top three slots in the 2016 Tech Talent Scorecard, according to Real Estate Weekly. These markets have highly educated workers, prominent universities and lots of Millennials. New York and Austin round out the top five.

Rent growth in these regions has mirrored the economic bubble. Bay Area rents are now nearly two times what they were in 2011.

Cities such as Nashville, Charlotte, Tampa, Seattle and Phoenix are gaining momentum. Nashville grew at 68%. Demand for tech workers has surged in these secondary cities, according to the report’s author. The Tennessee capital also has the lowest vacancy rates of all the cities CBRE ranked.

Rent growth is most prominent in the large tech markets with office rents in the San Francisco Bay Area nearly double what they were five years ago. But the decrease in vacancy rate is present across both large and small tech markets, with the Nashville vacancy rate the lowest of the top 50 tech talent markets. [REW]