Compute percentages changes across time
Arguments
- df_flr
- Dataframe input, output of - PrjCompPPTS::ff_ppts_lrce_flr
- ar_it_years_chg
- Array of integer, years to select for computing changes 
- verbose
- Boolean print details 
- ls_chg_year
- List of Array each array with start and end date and list contains new variable names 
Author
Fan Wang, http://fanwangecon.github.io