Your numbers make sense at first glance, but there are a couple of points that should be born in mind.
1. The numbers you give need to be adjusted for 2 factors: priestly dropout rate and the age of ordination. The dropout rate over the past couple of decades has been horrendous, but even assuming that the worst of that problem is over (a pretty big assumption considering the present abuse crisis which has not finished playing out), still there will be a dropout rate which is more than negligible. Secondly the age of ordination is much higher. 40 years of active service would have been a safe bet a couple decades ago, but today when I see news reports of ordinations, the average age of the ordinands is often around 40.
2. The mathematician who wrote the article "Springtime Decay" on Seattle Catholic would not agree with your hypothesis of a comparatively steady state. He predicts a continuing downward trend, based on the currently available numbers. It's impossible to know who will be proven right, you or the author of "Springtime Decay," but one must at least consider the alternative:
Actually, the drop-out crisis was ended around 1978 by the Vatican refusing further laicizations. The rate now is pretty low. The rate from 1965-1978 was off the charts.
still there will be a dropout rate which is more than negligible. Secondly the age of ordination is much higher. 40 years of active service would have been a safe bet a couple decades ago, but today when I see news reports of ordinations, the average age of the ordinands is often around 40.
I based 40 years on an average age of 35 at ordination with service until mandatory retirement at age 75. Admittedly, its a rough number, but we don't have much data on age at ordination to go on.
2. The mathematician who wrote the article "Springtime Decay" on Seattle Catholic would not agree with your hypothesis of a comparatively steady state. He predicts a continuing downward trend, based on the currently available numbers. It's impossible to know who will be proven right, you or the author of "Springtime Decay," but one must at least consider the alternative:
I base the steady-state prediction on the fairly stable number of ordinations and drop-outs during the past 25 years (actually, the ordaintions have first risen slightly, as one would expect with the larger cohorts of births from the period of 1957-1967, and then decayed slightly with the smaller cohorts of 1968 on). The decay we are seeing now is that the current ordination class is not replacing the very large ordination classes from the early 1960's (although admittedly, many of these men have dropped out years ago, so its not as bad as one might initially think), and the number of Catholics in the demographic cohort of age for the seminary is smaller than previously.
However, as I pointed out elsewhere, the number of Catholics being born began to rise again in 1988 after 20 years of decline, and has stayed about 15% higher for 15 years now, so in about 15 more years, we will have larger demographic cohorts from which to draw even if the birth rate drops off (which it currently shows no sign of doing). Also in about 15 years, the remaining useful years of service of men from the seminary boom of the 1960's will be over, and we will have mostly the Priests from the steady state period of the mid-1970's onwards. The convergence of these trends, combiend with a rough loss of about 1000 priests per year on average to excess natural mortality and defections during the next 15 years will produce my predicted plateau of 25,000 priests.
The actual number of active Catholics to be served would appear to be holding steady around 15-20 million, as the registered population grows but the percentage attending Mass continus to slowly decline. So we will continue to have more priests per active Catholic than we did in the 1950's, when we had about 35,000 priests for 30 million active Catholics.
The only reason to believe this trend wouldn't come to pass would be a large shift in the aggregate number of active Catholics (up or down).
Actually, the drop-out rate is down very sharply throughout the 1990s. Apparently, there was a huge lot of hippies who thought the church was going to become something very different than it is now, and when it did not, they left. The age of the horrendous priestly exodus is over.
By the way, I do not mean to disparage some very good men who left the priesthood for sound reasons.
As for the author of Springtime Decay, the application of exponential rates to any trend always creates laughable situations in the future. He acknowledges that "The last two actual data points are higher than the exponential decay function." From the wording he uses, one gets no sense the last data point is DOUBLE his expected value. And his modified slope corrects for the second-to-last data point, throws other data points off, and still underestimates the final data point.
This is no reason to dance in the aisles, for sure. What's happening is what always happens when you apply a rough exponential formula to actual data. The slope is applicable for some period of time while the highlighted issue remains the dominant factor. As the numbers change drastically, the a different factor assumes dominance, and an inflection point is reached.
This of course supports, rather than dispoves, that there was a very dominant negative factor over the past 40 years. And the emerging significance of a second factor means only future stability, not a trend reversal.