Is there any current research on the use of different DBMS's in the world?

I do not know if it is the correct place for this but I would ask of you or get a light to this question, for purposes of undergraduate work fine:

Is there any current research (or not it fairly outdated) on the use of different DBMS's world?

I am interested in knowing the use of PostgreSQL.

Here are some queries to google I made:

rdbms what is the most used in the world?, rdbms global usage reasearch, rdbms global usage, usage statistics of the world postgresql, statistics by using the postgresql world RDBMS used in the world, usage statistics relational databases worldwide, RDBMS using statistics around world.