Some sociology of philosophers is included in histories of philosophy and in the biographies of philosophers. But the first systematic, statistical approach of which I am familiar was that of Pitrim Sorokin, a sociologist at Harvard. His findings are presented in vol. 2: A Study of Change in Major Systems of Art, Truth, Ethics, Law and Social Relationships of his four volume Social and Cultural Dynamics, 1937.

With the collaboration of two Russian philosophers, he devised a set of criteria and a scale of 1-12 to represent the influence of particular philosophers, and they proceeded to scour through the literature of the history of Western philosophy to determine various tendencies. Their results were represented in various tables and charts. Here is one of their charts, titled "Fluctuations of the Influence of Systems of Truth (by Centuries)":

Partially inspired by Sorokin's efforts, I have done a statistical survey of the 100 most influential philosophers of the past 50 years. Interestingly, some of my intuitions were confirmed, but there were also many surprises.

Here are 10 charts representing the standing of the philosophers who were ranked 1-100.

1-10
11-20
21-30
31-40
41-50
51-60
61-70
71-80
81-90
91-100