Since we're talking about the Model 3 and the Bolt, both all-electric vehicles, it's important to differentiate between only electric and the various hybrids. That 2.1% figure in China includes all variations of plug-in electric hybrids.
There were 26,373 plug-in electrics of all types sold in the US in March, a 42% increase over the prior year, and about 1.6% of all vehicles sold.