Interesting point, which does lead one to wonder what's going on and what is reliable information. I am going from the EIA statistics published today. If you look at PEMEX's own website, the production numbers are consistent with the US EIA, show 2005 production the lowest since 2002 (although by a small amount - that's what I mean by gradual decline), and are much lower than the IEA numbers you cite. BTW, the PEMEX liquids numbers do include condensate. I really wonder where the IEA numbers come from - apparently not from PEMEX. I am open to whatever the truth is.
Earl, what is the link to your source?
PEMEX link is:

http://www.pemex.com/files/dcpe/eprohidro_ing.pdf

EIA link (includes other countries also):

http://www.eia.doe.gov/emeu/ipsr/t22.xls

This link, just put up, also discusses Mexico:

http://www.energybulletin.net/11370.html

I have made watching Mexican production a hobby the last 3 years. They are perhaps the most key, as our second largest source of imported oil and closest to severe decline. PEMEX publishes numbers for each previous month on the 17th or 18th.

Thanks Earl. Very interesting stuff.