An idol's salary

these are estimates by the magazine, so they all might simply be wrong lol
so I suggest not worrying too much over these figures, altho they might be useful in a very rough sense I guess

 

probably in 2014 she's having a kennin post which amplifies her income....
for manatsu, I think it's because she got solo variety jobs more than ikuta

edit: agreed with rust, it's a magazine publication that probably only measuring solo jobs and within group these idols got... we'll never know the truth or the system within the management, they never publicly release their cash flow. It even unclear that these numbers are net numbers or gross numbers (tax, management cut, etc)