Sentence:  In Ireland, where 14.5% of the population are jobless, emigration has climbed steadily since 2008, when Lehman Brothers collapsed and the <WSD>bottom</WSD> fell out of the Irish housing market. In the 12 months to April this year, 40,200 Irish passport-holders left, up from 27,700 the previous year, according to the central statistics office. Irish nationals were by far the largest constituent group among emigrants, at almost 53%. 
Meaning of the word marked with <WSD> tags:  The lowest part of a container.