That long term unemployment number is as a percentage of unemployed people, per the link you posted. The department of labor (the bureau of labor statistics) calculates unemployment with a national household survey:
The world bank unemployment numbers (which are actually gathered by the international labor organization) are just a regurgitation of the BLS numbers above, which you'd know if you'd bothered at all to investigate the numbers you are quoting above.
(look at the metadata for the source)
(each country has it's own source, methodology, etc).
Valid complaints would be that the numbers reported don't include the homeless (although those estimates are gathered elsewhere), you don't understand the report, or that it conflicts with your personal opinion.