This number is expected to go down.
For a list of blood type frequencies worldwide including the rh factor, see:
https://www.rhesusnegative.net/themission/bloodtypefrequencies/
Population projections for 2050 indicate major increase of populations within countries below the 6% worldwide average vs. countries above the 6% worldwide average.
Map of countries by fertility rate (2018), according to CIA World Factbook
The world population is expected to rise from 7.7 (now) to 9.8 Billion people by 2050 with Asia expected to rise from 4.5 to 5.26 Billion, Africa from 1.2 to 2.53 Billion and Europe to go down from 0.74 to 0.72 Billion.
After spending a couple of hours examining individual projections and looking at frequencies current, I have concluded the following:
In the year 2050, rh negative frequencies worldwide are likely to be somewhere around 4.5%
Projections for the year 2,100 indicate a further drop to 3.2%, possibly as low as 2.7%.
In no way does this indicate extinction being on the way, but it does show a stern trend. And since we cannot predict what types of world events, diseases or additional circumstances may impact rh negative frequencies, the above is not to be held reliable other than what will take place if trends continue as current.