Now that I read your post, I do realize that I mainly vote for "friends" or the steemians who welcomed me to the platform.
Although I think it is a normal thing to do, I kinda want to start engaging with more people, which thinking better I'm already doing since the end of last year when I created my contest free to play (focusing mainly on smaller accounts and newcomers).
I don´t know if you can create a correlation with the votes attributed to accounts created on the same month.
It's common I think, and nothing bad.
December 2017 and January 2018 were busy months, and so like others you have a good amount of votes in this area. A big spike at August 2016, the month my account was created. Looks like lots of votes for a few accounts, lucky them :)