Pew 2021: 47% of currently married non-O Jews are intermarried, with 60% of those who married after 2010 and 18% of those before 1980. So, for those who are 40 y.o. numbers are like Avira says or higher.
other findings:
First intermarriage is quickly followed by 2nd: among those who have one Jewish parent, 80% have non-Jewish spouse.
40% Of R- have some “in common” to O-. 76% of C-s. No branch 24%/
50% O- feels some in common with R-, 63% to C-. So, it is about mutual.
Interestingly, in each group there are 7-9% of those who do not feel in common with their own group.
Among 65+ 44% are R, 25% C, 22% none, 3% O
Among 18-29, 29% are R, 8% are C, 41% are none, 17% are O