. By ▁the ▁end ▁of ▁ 2 0 0 8 , ▁that ▁figure ▁had ▁ris en ▁to ▁ 1 , 8 6 0 , 0 0 0 ▁- ▁an ▁increase ▁of ▁ 2 1 1 , 0 0 0 ▁and ▁nearly ▁ 1 3 %. By ▁March ▁ 2 0 0 9 , ▁un emp loyment ▁had ▁increased ▁to ▁more ▁than ▁ 2 , 0 0 0 , 0 0 0 ▁- ▁the ▁highest ▁level ▁the ▁nation ▁had ▁seen ▁for ▁more ▁than ▁ 1 2 ▁years . It ▁reached ▁ 2 , 2 6 1 , 0 0 0 ▁by ▁June ▁that ▁year , and ▁by ▁April ▁ 2 0 1 0 ▁had ▁exceed ed ▁ 2 , 5 0 0 , 0 0 0 ▁for ▁the ▁first ▁time ▁in ▁ 1 6 ▁years . ▁ ▁Conf ounding ▁variables ▁in ▁determ ining ▁cause ▁and ▁effect ▁The ▁caus ality ▁linking ▁job ▁losses ▁to ▁reduced ▁business ▁re venue ▁is ▁obviously ▁ground ed ▁in ▁reality , ▁at ▁least ▁to ▁a ▁large ▁extent . ▁After ▁all , ▁it ▁is ▁self - ev ident ▁that ▁a ▁firm ▁with ▁one ▁million ▁dollars ▁in ▁annual ▁re venue ▁cannot ▁pay ▁a ▁two - mill ion - d ollar ▁annual ▁pay roll ▁without ▁going ▁into ▁either ▁deb t ▁or ▁bank rupt cy . ▁However , ▁at ▁least ▁some ▁of ▁the ▁apparent ▁or ▁alleg ed ▁caus ality ▁is ▁difficult ▁to ▁confirm ▁quant it atively , ▁because ▁the ▁data ▁collection ▁and ▁analysis ▁that ▁would ▁be ▁required ▁to ▁do ▁so ▁faces ▁high ▁bar riers ▁to