After some further analysis, I determined a formula for a population’s average stress as a function of violent crime rate, which turned out to be parabolic (a second order polynomial). What I’ve been calling “power” (combining both increases in the minimum, and decreases in the maximum) is also a parabolic function of the violent crime rate. Reviewing the historical record of violent crime rates, I was able to construct a new view of the past 30 years.
From 1975 to 1980, stress increased while minimum power decreased. From 198o until 1985, the stress declined slightly and minimum power increased. From 1985 until 1990, stress increased dramatically, corresponding to a similar decrease in minimum power. During the following two years, with minimum power as low as it could get, maximum power decreased. In 1991, both stress and power leveled out. From 1991 until 1995, stress declined while maximum power increased to its 1990 level. From 1990 until 2000, stress decreased (as fast as it had increased before 1991) to roughly its 1985 level while minimum power increased. Stress and power began leveling out through 2005.