...the totals are down -12% from last month (not a surprise) and down -7% from last April, (which is a surprise).
My experience is the same. Site-to-site, not much difference. But my totals are down -16% from last month and down -8% from last April. A very unpleasant surprise, indeed.
Since I started doing microstock in 2005, this is the first time that my year-over-year revenues for a month are down (and I have been submitting new images at about the same rate as always).

The same happened to me! For the first time the earnings from a specific month, were lower than the same month of the previous year!
Now I'm getting worried.
Is this a prediction of something bad about to happen to the economy? I remember the September of 2008 which was almost equal to August, and suddenly, full blown crisis...
In fact, April was the worst month since August 2009!
Besides that there was a drop in the total earnings even if the earnings percentage were somewhat similar to March, except for a bigger drop from IS.