Hi math friends, I'm trying to derive a line of best fit for the data points in the image.

So for starters, what type of line is this anyway?
-the y intercept is (0,6)
-there seems to be a horizontal asymptote at about y=26/27.
Though I know it isn't cubic, I was able to fit a cubic line perfectly up until x=1,900 but then it shoots upward off the charts.

I was thinking log of some sort...thoughts?