Charlotte-Mecklenburg Schools' work force has shrunk by 6 percent in the past year, contrary to a tally on the district's Web site indicating it has grown, officials said this week.CMS's online “Fast Facts” says the district has 19,953 employees, including 9,363 full-time teachers, for 2009-10. When the Observer got a CMS payroll database in April, before a massive round of layoffs and subsequent rehiring, CMS listed 19,769 employees, including about 9,200 teachers.Two weeks ago, the Observer requested a year-to-year comparison of employees, to determine whether the payroll had grown or shrunk amid the budget-driven turmoil.