One thousand millionaires in Maryland have disappeared

I wonder why:

Maryland couldn't balance its budget last year, so the state tried to close the shortfall by fleecing the wealthy. Politicians in Annapolis created a millionaire tax bracket, raising the top marginal income-tax rate to 6.25%. And because cities such as Baltimore and Bethesda also impose income taxes, the state-local tax rate can go as high as 9.45%. Governor Martin O'Malley, a dedicated class warrior, declared that these richest 0.3% of filers were "willing and able to pay their fair share."