Had a big jump last month - just attribute it to higher than usual zooms
I usually like to check what was zoomed - last month one of the zooms done was for a search that was conducted via the Alamy image code. I thought that would result in a definite sale, but no sales showed up. This morning the sale showed up for that image.
Zooms are good in the fact that someone took a second look at your images, but only sales really matter, and for me they are few and far between.