How to map If transaction data fields increases?

Hi

I am loading approx. 10 years of transactional data(CSV) if transaction data fields increases how to map them?

For example: Now currently total fields are 20 so I create 20 InfoObjects.

In 2012 total fields are 18

In 2009 total fields are 14

In 2004 total fields are 10

When load I load transactional data from 2004 to 2008 I only map 10 fields other 10 are empty.

When load I load transactional data from 2009 to 2011 I need to remap 14 fields other 6 are empty.

When load I load transactional data from 2012 to 2013 I need to remap 18 fields other 2 are empty.

Is above procedure is right or there is an other way?