Which religion holds on to its members best?

The General Social Survey asked Americans their religion at age 16 and also at their current age. The first number you see includes results from 2000 to 2016 (N = 22,659), and the next number shown in parentheses refers to the period 1973-1999 (N = 36,286):

Percent of members not changing their religion
Jewish  81.7  (85.1)
Protestant  79.9  (89.2)
Hindus  71.1  (40.0)
Islam  69.4  (60.0)
Catholic  68.5  (80.2)
Orthodox Christian  68.4  (80.8)
None  59.2  (47.8)
Buddhism  55.0  (66.7)

First, most people do not switch, but Jews switch least.  You'd expect Protestants to be toward the top since they are a huge group, and one could switch from one denomination to another and still say he didn't switch away from Protestantism. This is not the case for small groups like Jews. It is impressive that members of some small groups, surrounded by a sea of people from other faiths, tenaciously hold on to their religion. I consider this to be a measure of a group's chauvinism.

Look how the general trend has been more switching in the more recent period. Don't trust percentages for small groups because they are based on tiny sample sizes. By contrast, the greater tendency of "Nones" to stick with their non-affiliation is probably real. More switching by people who grew up Catholic also seems to be a thing.

When people switch, where do they go? Let's list the modal category for the later and earlier period (in parentheses):

Most popular (non)religion to which one switches

Jewish  None  (None)

Protestant  None  (None)

Hindus  None  (None)

Islam  None  (None)

Catholic  None  (Protestant) 

Orthodox Christian  Protestant  (Catholic or None, tied)

None  Protestant  (Protestant)

Buddhism  None  (None)

In both time periods, the most common switch is to no religion. Quite a few Nones switch to Protestant in both periods -- I assume this is often evangelical.  The numbers are too small to make anything of the Orthodox pattern, but Catholics used to most commonly switch to Protestant, but now are more likely to switch to nothing.

Keep in mind that all this switching to no religion doesn't mean people drop all religious belief and practice.  In the latter period, 58.1% of Nones pray. There has been an increase in disbelief but also an increase in the deinstitutionalization of belief. (On the other hand, 88.6% of Nones prayed in the earlier period.)