From Statista:

Despite robust growth and record levels of electric vehicle sales in most of the largest automobile markets, combustion engines still dominate passenger car sales around the world. The share of plug-in electric vehicles in total passenger car and light vehicle sales/registrations was below 5% in all but four markets in 2018, with Norway the most notable exception at 49%.

Why is Norway in the lead? Its policies (e.g. tax exemptions, toll exemptions and other incentives) have been highly effective in promoting electric cars, but its policies cannot be easily transferred to other countries. The country imposes hefty vehicle import duties and car registration taxes, which makes cars significantly more expensive than say in the United States. By waiving these duties for electric vehicles, Norway is effectively subsidizing EV purchases at a level that a larger country such as the U.S. couldn’t afford. In addition,  Norway is a very wealthy country (ironically thanks to its oil reserves) with a high level of income.