From BfaR:

In a stellar book titled Why Civil Resistance Works: The Strategic Logic of Nonviolent Conflict, two brilliant young American academics, Erica Chenoweth and Maria J. Stephan, did something that no scholar before them had done: they looked at every conflict they could find between 1900 and 2006, 323 in total, and analyzed them carefully to see which succeeded, which failed, and why. Their findings were astonishing. “Nonviolent resistance campaigns,” they discovered, “were nearly twice as likely to achieve full or partial success as their violent counterparts.” Or, if you’re a fan of exact figures, here’s the score: Take up arms, and you have a 26 percent chance of succeeding. Practice the principles you have just read about in this book, and the number shoots up to 53 percent. Not surprisingly, if you look at the same statistics in the last two decades alone—with no more Cold War to spur the financing of armed conflicts across the globe—the ratio spikes even more dramatically in favor of nonviolence.

Countries that experienced nonviolent resistance, Chenoweth and Stephan found, had more than a 40 percent chance of remaining democracies five years after the conflict ended. Countries that took the violent path, on the other hand, had less than a 5 percent chance of becoming functioning democracies. Choose nonviolence, and you’re looking at a 28 percent chance of experiencing a relapse into civil war within the decade; choose violence, and the number is 43 percent. The numbers are uniform, and what they tell us is irrefutable: if you want stable, durable, and inclusive democratic change, nonviolence works and violence doesn’t.

Aaron McGruder gave a talk to some university students around 2000 that laid out this exact idea. He didn't sound hopeful that change would happen.

Edit: it seems to have been 2003