@village we should never extrapolate our own experience in a local kingdom hall to the rest of the world. But just look at the bigger picture, results and statistics over the years.
based on that we can make a fair conclusion that there is growth and that for the most part this growth comes from outsiders and not born ins.
average annual death rate 0.8%
average annual nr of df'd/da'd 0.4%
average annual birth rate 1.5% (at most as explained above, but probably less. Besides that how many of them will eventually become a JW?)
average annual growth rate (for lets say the last decade) more than 2%
Talking about personal experiences. The congregation i am in (this is my fourth year in this congregation) baptised during that period 5 persons. All of them were not born ins and were recruited through the preaching work. None of them is 'mentally unstable'. Also added are 3 unbaptised publishers, also no born ins and brought in via the preaching work. One of them will be baptised this summer at the district convention.
I live in a highly secular western society. People here have high incomes and high levels of education. I just tell this to show that personal experiences at a local kingdom hall won't show any of us the big picture.