I think it's important to reiterate that the "55%" is just for the last two years, not eight.

However I don't understand why SE talk in percentages. It has absolutely no bearing on how long development takes. There are so many major stages in development that there's stages within stages. Alone pre-production could take much longer than actual production. Basically what I'm saying is that 45% they have left to develop could take three months or it could take another two years.