I've been collecting data on the number of bomb shelters in various Russian cities. This was a topic of major debate decades ago, when some analysts argued that the Soviet Union pursued a "war survival" capability in order to undermine America's nuclear deterrent. I'm getting some really interesting stuff out of the archives here, which I'm going to use to craft an article about the USSR's shelter system. Here are some figures that have come out in recent years:
St. Petersburg: 4003, 2873 in housing sector
Tula: ~300, approximately 100,000 spaces
The CIA estimated in 1986 that the USSR had shelter space for 11.2% of its urban population. Between these figures and what I've seen in the archives, I believe that this estimate was approximately correct.