Since the inception of the IQ test, scores have been steadily rising. This is called the Flynn effect. The prevailing theory is that this occurs because we live in a more symbol-rich environment that promotes abstract thinking more than ever before (we read, interact with software, websites, stories, video games, etc).
According to award winning cognitive scientist Stephen Pinker: “if we take the Flynn Effect at face value, a typical person today is smarter than 98 percent of the people in the good old days of 1910. To state it in an even more jarring way, a typical person of 1910, if time-transported forward to the present, would have a mean IQ of 70, which is at the border of mental retardation.” (See more on Stephen Pinker: http://en.wikipedia.org/wiki/Steven_Pinker)
While the average person today is below the intelligence of giants like Einstein, the average person today is likely to be significantly more intelligent than their great-grandparents a hundred years ago.
But don’t celebrate yet, if you can’t spell and use grammar, you are probably not included.