I suppose one correlation is missing: the price of a number of goods generally considered valuable has gone down and the quantity and availability has gone up since the 80's. Think TVs, car radios, stereo systems, computers. If you really think you want one, you can buy it second-hand for so cheap that crime doesn't pay off. And if you steal one, you'd have a much harder time finding a place where you can sell it for some reasonable amount of money. Because crime involves a risk, it also requires proportionally a bigger payoff. Regular households don't provide that so easily anymore.

Another thing is that the illegal nature of a crime is a deterrent for most people but not so if you grow up in a culture where casual crime is no big deal. But cultures change: maybe there's less people exposed to that than earlier. Or because of the first point, casual crime has gone down because the payoffs aren't high enough, and this has been shrinking the relevant subcultures that earlier favoured committing petty crimes, thus reducing the number of people used to do crimes and therefore, eventually, full-time criminals.

Generally, a crime nearly always happens for a reason: a crime can happen only if someone wants something and there's no other way as easy to get it than to commit a crime. To summarise, a crime happens because someone wants to achieve a goal. In a crime there's always a risk involved: you might get into a fight, you might get caught, or you might get shot. Thus, nearly nobody does crimes routinely just for the fun of it: the payoff must be good enough, and the payoff generally correlates with the risk.