No, there is no reason to expect they should be more equivalent. They did not start out equal in size (10 tribes vs ~3 tribes) and their histories have been almost totally different, not parallel. By the time of or their separate diaspora, they were a full order of magnitude (that's x10) apart. (North = ~5 Million, South = ~500K.)
Furthur, the Northern Kingdom has experienced steady ~exponential growth over the past 2,700 years, interrupted mainly by natural disasters such as the black death, which also affected others. The Southern Kingdom however has experienced numerous periodic political and social upheavals which repeatedly decimated it's ranks.