Mathematically it is very easy to work this out and to do a comparison.
The anual number of divorced in a nation (divided by) the total population (multiplied by) 100. Basically this gives the number as a percentage, or out of 100. In other words this breaks a hugh number down so a person can see it better . Then you have to multiply that number until you get to a full number which represent the number of years. Hope this isnt confusing.
For example
if the divorce rate in a given year for a nation was 9000 and the total population of of that nation was 5,000 000. It would be 9000/5,000000 (multiplied) by 100 = 0.18. So in other words for ever hundred people in that nation there would of been 0.18 of a divorce. It is impossible to get 0.18 of a divorce so what we have to do is multiply that number (0.18) until we can get can get to a full number (and this would represent the number of years).I will now show you this as an equation.
9000 / 5,000000 x 100 = 0.18 per annum.
0.18 x 5.6 = 1.008
So what I am trying to say here is in a congregation of 100 publishers you would have to have 1 divorce around every 5 and a half years to be at the national average for that country. So what you now have to do is look at the cencus report for you country and work it out. Once you know what the national average is, think back over the years and think how many many have split in that given time and adjust that figure by the number of publishers. I know in the congregation that I am associated with (when I was researching this)I was shocked to find that the divorce rate over the last 2 decades was nearly 200% higher than the national average. Oh and until this point I always thought witnesses had an extremely low divorce rate.