In 2018, 60 is the most common age for an American (U.S.) Leon who is registered male with the Social Security Administration. It is the 485th most common male first name for living U.S. citizens.
Although it is currently enjoying steady popularity in Scandinavia and in the British Isles, it is actually more popular in Germany than any of those other areas. In the United States, however, it is considered to be in the same category as Elmer, Mortimer, Lester, Irving, and Wilbur in terms of being much less common today than it was a century ago.