Methodological note: The three words have to be graphed separately because they appear with significantly different frequencies. "Civil rights," for obvious reasons, appears much more often than "black power" or "outside agitator." When graphed together, the scale of the vertical axis makes it difficult to see the relative increase of the less prevalent terms. Still, what's important and revealing is the almost exact correspondence in the relative rise of each of the three terms over the course of the 1960s, through the civil rights movement and urban rebellions, and the subsequent decline over the course of the 1970s.