The answer to your specific question depends on whose data you look at. For instance, at this moment, Builtwith is showing approximately 53,719 Magento 2 sites live worldwide, out of a total of approximately 237,935 live Magento sites.
That's not to suggest that this data is perfect, but there's an implication that there are currently 3x-4x more Magento 1 sites than Magento 2 sites. Even if the data is slightly outdated, I think it's fair to suggest that Builtwith is seeing at least 2x more M1 instances than M2 instances.
However, it's not surprising that folks on old Magento 1 sites are looking to squeeze as much use out of their investment into their old websites as possible.
On the other hand, if you were to ask about the amount of new Magento launches happening on Magento 1 vs Magento 2, I think that you'd see a negligible amount of M1 launches. Merchants aren't choosing to build sites on Magento 1 today. There really isn't a good argument to build on Magento 1 today. Magento 2 launched in 2015, and is the new standard.
If you're looking to understand more of the differences between Magento 1 and Magento 2 from a merchant perspective, listen to Episode 2 of The JetRails Podcast, which is all about the Progression of Magento 2. You'll find some great info about features that aren't in M1, but that were added to M2 - including iterative updates in the last few years.
Best of luck!
