Enter notes in the rhythm that you want the strums. Attach chords to the notes. Select the staff, and apply the staff style Rhythmic Notation. Mute the notes.
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PrintMusic 2004, 2006, 2008, 2009, 2010, 2011; Finale 2010b, 2011b, 2012c, 2014
Mac OS 10.9, Windows 2000, Windows XP