I am not really concern about popularity, but the development side of it. Or, can the current size of usage / ecosystem be sustainable for FreeBSD long term development? Cooperate usage will at least paid for the development in Linux, I was just worried FreeBSD usage is shrinking because of this.
Honest question though: Does the popularity of an OS really tell us anything useful? I often use the "if it's popular, it's probably good" metric, but I know I am just being lazy...
As a curiosity, knowing the "rank" of an OS is interesting, but if I am making any important decisions, I research the OS myself, hopefully disregarding outside influences.