Some datapoints from his slide deck:

• India will remain the largest offshore market for many years, but growth is slowing due to escalating labor costs, a tightening agent market, and global offshore competition. His data shows 95,000 offshore outsourced agent positions in 2005, growing to 169,000 in 2010. One of the key drivers he cites is the fact that an IT/technology/engineering mindset is prevalent in India, with data protection and security rising to meet western standards. However, India seems to be bearing the brunt of anti-outsourcing sentiment.
• There are a number of emerging African markets to watch, including Botswana (aggressive global promotion strategy and excellent incentives); Kenya (same population size as Canada with solid English language capabilities); Senegal (currently host to some French-speaking offshore outsourcing); and Ghana. In North Africa, Egypt will take market share away from Morocco.
• The Philippines is well placed to serve English speaking markets, especially the US, due to the presence of western multinationals. Labor costs here are higher than in India, but offshore outsourced agent positions is expected to increase from 33,000 in 2005 to 59,000 in 2010. The biggest attraction, Ryan says, is a cultural fit between the Philippines and the US due to historic US military legacy and the fact that local agents understand American commercial culture.
• Canada is a favorite among American investors, but is being hurt by the slide of the US dollar. Canada is one of the most mature outsourcing market; in 2005 there were 13,000 agent positions primarily serving US customers, projected to rise to 17,000 by 2010.
• South Africa continues to grow because of scalability, western affinity and public/private sector growth committment.

I've taken the liberty of consolidating his figures into a handy comparative table:

Note that these figures represent offshore outsourced agent positions, not necessarily total agent positions within a region. Some countries have large and thriving domestic and captive call center markets that dwarf the size of their offshore capacity - Canada for example.