Stats not adding up to 100

My download stats are only adding up to about 50%, and I think it's because the rest are still using older versions from more than 5 months ago (which is when the oldest v1.2.2 in the screenshot was deployed).

Is it normal for it to take several months for updates to deploy (to half of your user base)? Is there any way I can see percentages for all versions >0% so they add up to 100?