sharply from 4.6 to 13.8% among Michigan inmates, and more modestly in Florida from 5.0 to 9.1%) and assault (which exhibits slow but steady increases from 5.0 to 6.8% in Michigan and Pennsylvania, and from 2.1 to 4.0% in Texas), the contribution of violent offenses to the total is stable or, in the case of robbery (Figure 4-top), actually decreases during the 1980s. Only drug offenses (Figure 4-bottom) display widespread sharp increases as a percentage of total prison populations, especially after 1980.6
The proportional mix of crime types among inmates is a constrained relational measure: recent large increases in the proportion of inmates for drug offenses must be offset by corresponding declines in the proportions of inmates for other crime types. Such compensating changes in proportions could easily conceal real increases in incarceration for violent offenses. In order to better isolate patterns of incarceration for violent crimes, the crime-specific rate of resident inmates per 100,000 population is compared to the more commonly reported total incarceration rate.