Other code: loads data.table with option to write it for a given cut
get_nbf(year_start = 1948, year_end = 2014)
| year_start | start year for which we want data  | 
    
|---|---|
| year_end | end year for which we want data  | 
    
data.table aggregate
# NOT RUN { dt <- get_nbf(year_start = 1980, year_end = 2012) # }