Cost basis fluctuation of foreign rental property due to exchange rate each year, do we use CDN value or US value for deprecation

I have a Canadian property which had a Building value of 200k USD bought in 2011 which was 202k CDN in 2011 because of CAD dollar being stronger in 2011. I am trying to file form 3115 to catch up on missed deprecations.  Since than Canadian dollar has been falling every year.   Please note the value in the CDN dollars remains the same but USD keeps changing because of exchange rate as can be seen in this table. 

 

Could  I convert the cost basis in USD based upon yearly average exchange rate each year and then deprecate it or do I need to stick to 2011 exchange rate and use converted cost basis every year

 

Return YearCDN to USD Average exchange rate Land Value CDN  Building Value
CDN 
 Land Value
USD (Different each year due to change in exchange rate  ) 
 Building Value
USD
(Different each year due to change in exchange rate  ) 
20111.01 $  100,000.00 $     200,000.00 $          101,000.00 $       202,000.00
20121.012 $  100,000.00 $     200,000.00 $          101,200.00 $       202,400.00
20130.9710 $  100,000.00 $     200,000.00 $             97,095.41 $       194,190.82