There are different immigrant clusters around geography and industry. E.g. South indians are a majority in the Tech industry in the Bay Area, Punjabi migrants from North India work in more working class jobs - as taxi/Uber drivers and 7/11 or convenience stores clerks. And the Patel caste from the western state of Gujarat are known for their presence in the motel industry.

Based on my non-scientific observation of looking at the 300+ Indian origin folks in my LinkedIn profile, the upper castes are likely 60%, though they make up 10-15% of the population in India. The "middle" castes a. k. a Other Backward Castes or the so called merchant castes make up the remaining 35% and likely are 30% of the Indian population.