use updated OxEcon schema
calculate national growth averages for 2002-2007
remove non-atomic column to avoid trouble when melting
round to two decimal digits for a smaller data file
apply function in two steps as we need intermediate data.frame
calculate population and GVA dominance

These are other calculations which we are moving to the main data
processing stream from the separate tables used in the past.
remove /EC$/ from GVA indicator names
correctly remove /EC$/ from indicator names
merge in raw population data
add comment
add back Countries column