ProQuest Statistical Insight -- Includes state government and business statistical reports. 2,200 titles/year. Coverage from 1980; full text from 2007. (Also known as Statistics Reference Index, or SRI).
National Center for State Courts -- Includes resources, education, statistics, and more on a wide range of court-related subjects.
Michigan
Michigan Courts Statistics Reports -- Includes caseload reports, judicial resources recommendations reports, judiciary performance measures, and other statistical data.