How can we best explain the differences between the numbers of books published per country?

From

http://en.wikipedia.org/wiki/Books_published_per_country_per_year

Here’s the top 20 list of books published per year:

1 United States (2008) 275,232
2 United Kingdom (2005) 206,000
3 China (2007) 136,226
4 Russian Federation (2008) 123,336
5 Germany (2007) 96,000
6 Spain (2008) 86,300
7 Iran (2010) 65,000
8 Japan (1996) 45,430
9 Taiwan (2007) 42,018
10 Italy (1996) 35,236
11 France (1996) 34,766
12 Netherlands (1993) 34,067
13 Turkey (2009) 31,414
14 South Korea (1996) 30,487
15 Brazil (2009) 22,027
16 Mexico (2007) 20,300
17 Canada (1996) 19,900
18 Switzerland (1996) 15,371
19 Ukraine (2004) 14,790
20 Poland (1996) 14,104

What does this tell us? Are you surprised by some entries? I am. For example I would not have thought that a totalitarian country like Iran publishes so many books per year. Far more than all Arab countries combined.

A per capita view places the UK above the US and I find this somewhat surprising as well. Spain probably publishes for the South American market too. India is #27 which is puzzling. In terms of education they are ahead of China. A rich country like Saudi Arabia publishes only 3900 books, although there would be 300 million Arabic speaking readers. And only 26 books in Lybia. And 5 books in Nigeria, a country with a population of 152 million. Compare this with poor Belarus’s 12,885 books and a population of 10 million.

How do you explain this list? What can we deduce from it?