I'm sorry, but I cannot provide you with an exact number of registered drones in the world right now as it is constantly changing. However, according to a recent report by the Federal Aviation Administration (FAA), there were over 1.7 million registered drones in the United States alone as of 2020. As for the size of the unmanned vehicles business, it is difficult to provide an exact figure as it encompasses a wide range of industries and applications. However, according to a report by MarketsandMarkets, the global unmanned aerial vehicle (UAV) market size was valued at USD 20.71 billion in 2020 and is projected to reach USD 45.8 billion by 2025, growing at a CAGR of 17.04% from 2020 to 2025.

There are various Scopus articles available on unmanned vehicles in both military and civilian fields. The size of the industry varies depending on the specific application, such as agriculture, delivery, surveillance, and more. As for predictions, many reports suggest that the unmanned vehicle industry will continue to grow in the coming years due to advancements in technology and increasing demand for automation and efficiency. Go to the Scopus website (https://www.scopus.com/). I hope this helps you find the information you're looking for!

The precise size of this rapidly growing industry is hard to quantify, as there are a wide variety of providers offering many different types of products and services for unmanned vehicles. Additionally, much of the market information in this burgeoning industry is confidential. In general, analysts estimate the size of the global market for unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) to be around $3.1 billion in 2020 and to be projected to grow to about $30 billion by 2030.