LOS ANGELES (Reuters) - Some 20.6 million Americans watched President Barack Obama's inauguration ceremony and related events on television, according to ratings data on Wednesday. That's down sharply from his first inauguration in 2009. TV ratings company Nielsen said 18 U.S. television networks and cable channels carried live coverage over about six hours of Monday's swearing-in ceremony, speech and parade in Washington. Monday's TV audience was a drop of 17.2 million from 2009, when 37. ...