I think its interesting the way you (ITLD) count your first column, the worst seasons average wise would be those following heavy losses over winter, not often the case if taking the average from the number of surviving colonies in the spring as nature has a wonderful way of bouncing back, hard winters and late springs often preceding good summer flows.
Funnily enough it only loosely correlates. Summer weather is much more to the point. In a good season recovery from splitting is rapid and vibrant. Conventional thought says splitting hives to make up losses impacts harvest, and if you only look at the parent hive and discount the split(s) then you have a point, but a cortrectly timed split parent can be peaking again at just the right time and can do better than an unsplit parent suffering instability, and you have the harvest from the split to add in too if you wish to count it that way. The distinction between crop size and colony average is brought into focus here, where you can have a bigger crop but a lower average. At the end of the day its crop rather than average that pays the bills, but in itself that not a useful measure as you need to know about performance, potential, and shortfall as well.
However, the point you make is indeed partially valid, but we still count the dead outs in our column 3, as you spent money on feeding them and treating them for varroa, picked them up, moved them around, and apart from examination labour costs there is not much else they did not get. Their costs are counted and thus their returns need taking into account too, even if its zero.
Many beeks do not count any non performing or low performing colony in their averages, and to me thats just self deceiving nonsense.
You can also look at time and money expended per colony. You can spend endless time doing everything just perfectly (to your own eyes anyway) and get a great percolony average, but at what cost? I would sooner do a rapid system that was efficient rather than perfect and get a lower average per hive, but a bigger one per pound invested and hour expended. Its all very subjective indeed and there is often little to learn other than in the most general of terms from comparing relative averages between beekeepers. The variables that make it useless are many, simplest first question, often answered dishonestly, is 'How much have you fed the bees this year?'
Thats one hides a load of differentials. We give one full pre winter feed, c 14Kg, per colony, and *if needed* another 7Kg or so in spring. Another 7Kg in late June is under consideration due to the current pattern of the bees having a 'stop' at that time. Some who I have talked to are straight enough to admit to an annual feed level of as high as 80Kg, and 60Kg is not terribly unusual (seriously!!) in some areas (being careful not to point fingers here). These same beekeepers are then sometimes a bit disparaging about the poor averages of other beekeepers.