Some guy named Thomas says the following about people with an INTJ typology:

… if you encounter an INTJ (Introverted, iNtuitive, Thinking, Judging), there is a 37% probability that his IQ places him in the top 2 percent of the population. The probability is 20% for an INTP, 15% for an INFJ, and 8% for an INFP. These four types account for 66% of the high-IQ population but only 6% of the total population.

Which leaves this INTJ to wonder whether he is a monumental underachiever or if rather just unusually stupid.