What is the role of "booms"?
It is a plural noun: Originally U.S.
OED: 1.a. [...] a sudden bound of activity in any business or speculation.
1911 E. M. Clowes On Wallaby ii. 31 The Land Boom—‘the Boom’, as it is always called..had a most potentially humanizing effect on the people.
1936 M. Plowman Faith called Pacifism 28 The people of this country were enjoying a post-war boom.
1955 Bull. Atomic Scientists Mar. 88/2 Thus the uranium boom began.