Read this and answer the question. If the question is unanswerable, say "unanswerable".

According to recent estimates, 50% of the population adheres to Christianity, Islam 48%, while 2% of the population follows other religions including traditional African religion and animism. According to a study made by Pew Research Center, 63% adheres to Christianity and 36% adheres to Islam. Since May 2002, the government of Eritrea has officially recognized the Eritrean Orthodox Tewahedo Church (Oriental Orthodox), Sunni Islam, the Eritrean Catholic Church (a Metropolitanate sui juris) and the Evangelical Lutheran church. All other faiths and denominations are required to undergo a registration process. Among other things, the government's registration system requires religious groups to submit personal information on their membership to be allowed to worship.

How many people followed animism according to the Pew Research Center?
unanswerable