Estimates suggest there will be 25 million by 2100.

Estimates suggest there will be 25 million by 2100. Take a guess: electric vehicles, household robots, wild elephants, centenarians, or streaming services per household?
Electric vehicles. There may be far more than 25 million – estimates suggest 145 million – on the road by 2030.
Household robots. Domestic robots that offer companionship or help with tasks like lawn mowing, vacuuming, and mopping are becoming popular. Estimates suggest about 55 million domestic bots will be sold next year
. Wild elephants. From 1989 to 2018, the number of elephants in the wild doubled to 34,000, reported Earth.org.
Streaming services per household. Currently, the average number of streaming services per household is four. There's room for growth, but probably not that much.
Centenarians. The world is in the midst of a longevity revolution and, by 2100, there may be as many as 25 million centenarians – people age 100 or older – around the globe, according to a source cited by Science Direct.-+++++++++++-------+++++++++++