1- The way I see it, 'remained' and 'stayed' fit in right with the phrase 'the same'. As far as 'kept', it should be followed by something like "the same figures as that of" or something like that; it doesn't fully collocate with 'the same'; it nees somethinbg else for it to sound complete and convey an absolute meaning. 2- You either write: THE April socio-economic growth, or April's socio-economic growth: it all comes down to whether you put the article THE or not for you to know when to write the apostrophe.
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