CIA Revision Of Nigeria's Ethnic And Religious Statistics. Shock Alert!!

The Central Intelligence Agency- CIA, The much quoted American intelligence unit website has made a revision on their website's Nigerian section under People and Society, Ethnic groups as well as Religion.: Updated November 09, 2018.

According to them, this is the reflection of Nigeria's ethnic statistics:
Hausa 27.4%
Igbo (Ibo) 14.1%
Yoruba 13.9%
Fulani 6.3%
Tiv 2.2%
Ibibio 2.2%
Ijaw/Izon 2%
Kanuri/Beriberi 1.7%
Igala 1%
Others 28.9%
Unspecified 0.2%

It then goes on to say Muslims are 51.6% of the country, Christians are 46.9 (of which Roman Catholics are 11.2%), Traditionalists are 0.9%, while unspecified are 0.5%

But knowing that this same CIA is the same agency responsible for the much peddled Hausa-Fulani 29%, Yoruba 21%, Igbo 18% Ijaw 10%, Kanuri 4%, Ibibio-Efik 3.5% Figure that was brandished around for a very long time, is it safe to say these new figures are also unrealistic and suspect?

Also the way they seem to be able to arrive at such precise percentages, plus their inclusion of an "unspecified" category seems to suggest that they did some sort of survey?  (If they did, then when, where and how did it happen)

Take for example, How Igalas be 1% but Urhobos don't rank?
Hausas and Fulanis together are now 33.7% from 29%
Igbos are now 14.1% from 18%
Yorubas came as the biggest shock crashing down to 13.9% from a previous 21% More than 7% decrease.
Ijaws also went from 10% to 2% (This one I am not surprised, because trust me, everyone knew Ijaws were not 10% of Nigeria)

The consequence of this is that Hausas alone are now the same population as Igbos and Yorubas combined, without even factoring in the fulanis YET.

What actually happened? Are the new stats more believable than the old one from the same Agency, or are both figures old and new total crap, which would only suggest that this so-called agency are just amateurs sitting in some armchair in faraway Washington D.C making wild unresearched guesses? Hmmn.