If you consistently overestimated the number of people who would answer as you answered, you showed something called "the false consensus effect" (Ross, Greene, and House, 1977). People show a false consensus effect when they think that others think more like they do than is actually the case. The false consensus effect is common; you may have encountered it during classroom debates or conversations with your friends when you have been surprised to learn that your peers and friends don't have the same attitudes as do you.
