From the wikia:
Canon Non-Canon SBS Paramecia - 49* 15 2 Zoan - 17 3 0 Logia - 11 3 0 Unspecified - 0 1 1 Total Devil Fruits - 77* 22 3
It is clear that Paramecia users outnumber both Zoan and Logia users. Is there any specific reason for that?
I think that more Zoan users mean more animals, so it will have less creativity (for attacks) compared to other Devil Fruits. So that may be a reason for less Zoan users till now.
But what about Logia? Most Logia users are big-shots.