As an AI language model, I can provide information based on current knowledge up until 2021. However, it is important to note that personality types are not determined by specific years and do not change over time. The rarest personality type is subjective and can vary depending on the classification system used.

One popular classification system is the Myers-Briggs Type Indicator (MBTI), which categorizes individuals into 16 different personality types based on their preferences in four dichotomies: extraversion (E) or introversion (I), sensing (S) or intuition (N), thinking (T) or feeling (F), and judging (J) or perceiving (P).

According to the MBTI, the rarest personality type is often considered to be INFJ (Introverted, Intuitive, Feeling, Judging). INFJs are known for their deep empathy, intuition, and strong values. They are often described as insightful, creative, and idealistic individuals who are driven by a desire to make a positive impact on the world. INFJs are often seen as rare because they make up a small percentage of the population, estimated to be around 1-2%.

However, it is important to note that the rarity of a personality type does not necessarily indicate superiority or uniqueness. Each personality type has its own strengths and weaknesses, and all types contribute to the diversity of human behavior and perspectives.

It is also worth mentioning that personality typing systems like the MBTI have faced criticism for their lack of scientific validity and reliability. Therefore, it is important to approach personality typing with an open mind and consider it as a tool for self-reflection rather than a definitive categorization.