Crowded at the top

In the 260 weeks from 1966 to 1970, there were only thirteen musical acts responsible for every  #1 song on the Billboard charts.

In the 260 weeks that accounted for the first half of the 1970s, it was 26. (hat tip to John Marks for the stat).

Sometimes, we define a golden age in a market as a time of stability, when one or a few giants capture all of our attention. AT&T telephones, Superman comics, Beatles records, IBM computers, The New York Times... and now Google. Choices are easy, the...