I would be interested in seeing the numbers around Japanese, Korean, Hindi, Spanish etc. in my opinion, this may specifically be an avoid China phenomenon.
With Spanish learning rate would be high because it's just in general a very popular second language to learn, especially for Americans, regardless of any anticipated economic benefit.
With Hindi, English is also commonly spoken in India and a large portion of official business is done in English due to it being an option external from the many different languages spoken in the country. So there wouldn't be much benefit to learning Hindi specifically unless as a hobby.
Japan and Korea might be seeing an uptick in foreigners learning the language due to their cultural exports, which are increasingly popular in the West.