Downloads flat text file with BLS unemployment data. Parses just unemployment rate data from the download.
fetch_unemployment(url, min_year = 2010)| url | A string with the url of the flat text file.  | 
    
|---|---|
| min_year | A number with the first year of data to keep.  | 
    
A data frame:
series: BLS series ID
(see https://download.bls.gov/pub/time.series/la/la.txt)
year: Year
month: Month of the data (annual averages are "M13")
value: Unemployment rate
footnote: BLS footnote code
(see https://download.bls.gov/pub/time.series/la/la.footnote)
build_coc_unemployment() for building CoC-level unemployment rates