Actually Google AdWords says that you have an average of 40k searches per month for "bitcoin" in Nigeria and more than 1 mio. searches/month in the US.
Right but the map seems to present the data in a way that implies those searches for bitcoin in Nigeria are more popular than other searches for their given country.
That only indicates demand for botcoin, not the reason for demand. Though emerging markets adopting it might explain the growth. It doesn't help assess bitcoin's value except to indicate it might have additional stability as a currency in some small nations.
https://trends.google.com/trends/explore?date=all&geo=NG&q=b...
(it's for Nigeria)
And the global map for since 2004:
https://trends.google.com/trends/explore?date=all&q=bitcoin
With the search term being most popular in Nigeria.