I don't know about total population, but our kill rates increase each year from 20-30%. Based on the records that I keep, hogs tend to expand about a mile per year. This is based on acreage with river frontage and has pretty much been spot on. There is one exception, there is a piece of property that I hunt that is about 600 acres. It has big swamps, a creek from the river and multiple ponds on it. We have yet to see a pig track or any sign at all on the place. I have killed hogs on all three sides of this piece of property. The only theory we have been able to come up with is that the land owner keeps the property clean, as in there are no thickets, no palmettos, Buckbrush or pines. It's just old growth hardwoods where you can see a couple hundred yards in winter. When I say he keeps it clean, he will stop the tractor just to go cut a piece of river cane or a sweetgum that the bush hog will not reach.