Helpme

So I need some help with a program I am currently making, and wodnered if there was an easy way to make it. The function I need help with is this: There are 4 pumps, and 1 of them is going to start, after 10 sec shall the next start, so 10 sec after that the third one. And so like this it continues. But heres the clue. The pump which have been used the least is going to start first, if it is pump 1 that have been used the least, or if pump 3 has been used the least. If you know of any function block, or other way I can do to make this work, I would love the help.   (I know of the comparison blocks less than and more than, but with these I only can think of 1 way to make this work. And it would be over 48 function blocks, which I personally think is too much)

Hello. I have some issues with starting cx-programmer. It wont start. The start up screen shows, then closes, says that cx-programmer is running, but it is not, it is an empty window. When I look in task manager it says the program uses 0% of the processor, but it uses ram. Do you have any idea of how get the program to start the program again.