Tech's space appetite eclipses highs of dot-com boom

Technology companies have leased 40 percent more San Francisco office space since the start of 2010 than during the five-year dot-com boom.

The sector represented 61 percent of all office leasing last year, a historical high.

Since 2009, tech has created 23,500 jobs - 86 percent of all new office positions in the city.

[...] they're also a revealing glimpse into San Francisco's reliance on the health of a single sector historically prone to intense booms and busts.

[...] non-tech companies are actually contracting in the city.

Health and education inched forward, but the presence of business services, legal, financial and social services all declined in the past three quarters.

Apps, social media and cloud services have become a crucial part of nearly every industry, transforming business in a way that fly-by-night dot-coms never really did.

Changing face of techIn addition, the definition of tech has expanded to include education, entertainment, media, retail and basically any other business that develops an app or website.

Economist Ken Rosen, who famously predicted the San Francisco office market crash of the early 2000s, said that far more of the companies filling up the city's buildings today have real business models and actual revenue than the earlier wave of dot-coms.