The estimated writedowns include realized writedowns or loss provisions for 2007:Q2 to 2009:Q2 and expected additional writedowns or loss provisions: 2009:Q2 - 2010:Q4. According to the IMF up to now US banks have recognized 60% of anticipated writedowns, while euro area and UKI domiciled banks have recognized about 40 percent.

So the figures somehow include the fact that Euro area banks have written down less so far and should write down more in 2009 and 2010. Maybe some Euro area banks will and can (HTM) spread their writedowns over the next decade but I don't know how much this enters the data. 

Good point - I forgot this went through end of 2010. However, the banks are avoiding writedowns of assets they know are bad but won't come due for years. Wells Fargo in the US recently said that they were in a better position than other banks to avoid recognizing losses on Option ARMs because theirs don't recast for 10 years. So negative amortization can go on longer before people quit paying, yet they can book fewer writedowns!

I expect huge bank writedowns in 2011-2015. And idiosyncracies of laws and assets may have a lot to say about whether the writedowns occur by Q4 2010.