Lee & Low Books produced an informative infographic about the diversity gap in children's book.
Basically, the minority population is growing in the US but there's still a huge gap in the representation of multicultural content in children's book. According to them, there's been very little progress. Bear in mind that we have an African-American president, a popular TV show about Asian-Americans in Fresh Off The Boat, a major Hispanic-American TV station like Univision, and yet, diversity is still missing in the children's book industry.
Hopefully, this infographic is a wake-up call to the industry and will inspire writers/illustrators to produce more multicultural content.