Re: Maybe other causes?
It's more a question of miles driven. The UK with gas prices at about a weeks wages per liter makes people a bit more thoughtful before they get in the car and drive 100 miles. In the USA with gas priced at McDonald's lunch per tankful in cost keeps people on the road.
Automatic weapons? Anybody that has them usually keeps their mouth shut about it or the FBI, SWAT and a dozen other "official" state security thugs will break in, confiscate the weapons for shipment to the cartel in Mexico, shoot the owner in the head and claim that he made a threatening move. I would make a threatening move if I heard shouting outside my house followed by people smashing in the door at 5am. Somehow, the cops wonder why people present them with so many problems on these raids.