A table containing the hierarchy of SOC, with both labels and keys included.
Format
A table with the following columns.
- soc_1
- Major groups. The first two digits indicate the soc group 
- soc_2
- Minor groups. The first 4 digits indicate the soc group 
- soc_3
- Broad occupations. The first five digits indicate the soc group 
- soc_4
- Detailed occupations. Digits that indicate the soc group