We tend to confuse normal business cycles with rallies. A business cycle reflects the expansionary and recessionary phases of the economy, usually in the neighborhood of four-to-six years. A rally refers to a recovering stock market (which should not be confused with economy) that occurs after a 30% decline in stock prices. In the last 116 years, we have seen thirteen rallies, averaging about nine years each.
You can see the rally in the Dow since the bottom in March of 2009 is about average in duration but much weaker than the average rally, despite setting a new market high yesterday. The bottom line is that history gives us no reason to suspect a market collapse is due. There is still plenty of room for the bulls to run!