The percent will be the total number of speakers for the seven listed Bantoid languages divided by the total population of Kenya. At the bottom of the first column, the total number of Bantoid speakers is about 14 million, while the total population of the country is about 22 million. So the percent we want is around $$\frac{14}{22}$$. This fraction must be a little LESS than $$\frac{2}{3}$$ or $$66 \frac{2}{3} \%$$, since $$\frac{14}{21}=\frac{2}{3}$$. The best choice is $64 \%$.