Tobacco companies involved in a 1998 landmark settlement transferred about $50.9 million to Iowa’s treasury on Thursday, Attorney General Tom Miller’s office announced. In the last 20 years, Iowa has received more than $1.2 billion in payments under the settlement. The state will continue to receive annual Master Settlement Agreement payments in perpetuity, based on the number of cigarettes sold in the United States. The MSA is the largest settlement in U.S. history. About $11.2 million of this year’s payment — or 22 percent — will go to the state. The 78 percent remainder will be used principally to pay bondholders who bought bonds issued by the Tobacco Settlement Authority.