
Place one of these four characters: @ # $ % in each of the sixteen squares so that no character appears more than once in any row, any column, or any of the two main diagonals.
Use Excel or any suitable app to complete the puzzle.
Then take a screen capture/image of your solution and paste it into this thread (between spoiler tags) to supply your answer.
There may be more than one solution based on different combinations of the four characters, but any valid solution must comply with the parameters above.