Uhuru won by 93% in both 2013 and 2017 in Kiambu. Most of the kabilas are in outlying areas of Nairobi. I have heard that Luo and Luhya politician pay them to register in Nairobi - and they get paid to go and vote.
So while other areas were doing 98% - Kiambu did 93% - telling you only about 5% of Kiambu were non-gema.
This was 2017
VOTING BY COUNTY
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CENTRAL PROVINCE
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KIAMBU COUNTY
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Registered voters: 1,181,076
Votes cast: 988,980 83.7
Invalid votes: 3,828 00.4
Valid votes: 985,152 99.6
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Candidate Party Votes %
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Ekuru Aukot TAK 761 00.1
Abduba Dida ARC 344 00.0
Cyrus Jirongo UDP 154 00.0
Japheth Kaluyu 1,028 00.1
Uhuru Kenyatta * JPK 912,588 92.6
Michael Mwaura 320 00.0
Joseph Nyagah 767 00.1
Raila Odinga NSA 69,150 07.0
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Total 985,152
I think this is the case,if they were to vote in Kiambu figures would be shocking,Kiambu Kikuyus are not giving birth and these kabilas really are,so maybe if they stay vote in next decade it will be Kikuyu 55% vs Kabilas 45%
Then there are the children sired by luhya farmhands i don't know what population they would make but from social media it appears to be high