Florida inmates convicted of non-violent drug crimes spent 194 percent more time behind bars in 2009 than they did in 1990, costing the state billions of dollars but providing little public safety benefit, a new study found. The study, by the Pew Center on the States, examined trends in 35 states that provided data on incarceration for inmates convicted of violent crimes, property crimes and drug offenses. It found that nationally, state inmates across all categories of offenses served an average of nine additional months in custody, a rise of 36 percent since 1990.