What is "first-person pronoun density"?

In the Tunnel Wall

Obama's Narcissism Made Worse in First Year in Office  "Another sign of Obama’s growing malignant narcissism is his lowered Adversity Tolerance Threshold. I compared the number of times he snapped at critics and journalists during the election campaign and after he became President.

Understanding Obama: The Making of a Fuehrer  "I was not impressed by Sen. Barack Obama after the first time I saw him. At first I was excited to see a black candidate. He looked youthful, spoke well, appeared to be confident – a wholesome presidential package. It is so instinctive for most people to want to see blacks succeed. It is as if all humanity is carrying a collective guilt for what the ancestors of blacks endured. However, despite my initial interest in him, I was soon put off, not just because of his shallowness but also because there was an air of haughtiness in his demeanor that was unsettling. His posture and his body language were louder than his empty words." 

"When criticized, Obama's soul can be seen in his eyes."

In the Tunnel Wall.