For any kind of app targeting westen world (meaning - it's not localised into Hindi, African and Chinese languages), the market share of Lollipop will be below 20%.
According to most app stats I've seen (mine and others), Android 6.0+ is pretty much on 80%+, with Oreo nearing 40% since Samsung started rollouts.
According to most app stats I've seen (mine and others), Android 6.0+ is pretty much on 80%+, with Oreo nearing 40% since Samsung started rollouts.