When will all seasons of Spongebob SquarePants finally be available on Netflix?

So until now, Netflix only has season 7, season 8 and season 9 on it. There are no other seasons. And I wanted to ask you when will there finally be all seasons of Spongebob SquarePants? And why are not all the seasons on it?

Because the licenses might cost too much money for Netflix? Maybe just because you think that none of it is watched too little?

We can only guess about the reason and when or if there will be other seasons on Netflix at all.