Ten years back remittance was 31% of the GDP [1] - a massive number. It might have declined, but the tiny state accounts for 20% of India's inward remittance while holding a mere 3% of the nation's population. Wikipedia says that 3 million people are working abroad (mostly in the middle East), which is like 10 percent of the population (what percentage of the youth will that be?). Also, a very significant number of Malayalees work in neighbouring states - again due to Kerala having no industries.

I don't have numbers for the last ten years, but if remittance has gone down, it is also neck deep in debt. I am in Kerala quite frequently, and can confirm that there are no industries there - except for tourism, and some IT which is relatively miniscule compared to neighbouring states.

[1]: https://en.m.wikipedia.org/wiki/Economy_of_Kerala