TIOBE replaces their index content each month, so I quote:
“The top programming languages are in a long term decline: both Java and C have all time low scores in the TIOBE index. And almost all of the other top 10 languages are going down as well year to year. So what languages are taking advantage of this? It is all happening down in the charts around position 40. A new set of languages is gaining ground, notably Crystal (#32), Kotlin (#41), Clojure (#42), Hack (#43) and Julia (#46). Especially Crystal with its jump from position 60 to 32 in one month is doing very well. The Crystal programming language is a statically typed Ruby variant. Since it is compiled it is superfast and has a small memory footprint without losing the feeling of being easy to use. It seems worthwhile to give it a try.”
October: Crystal at #28, passing Scala.