There was a comment below on Indian American ethnicity in terms of proportion. By "ethnicity," I mean the dominant language-based groups which serve as the organizing unit of many Indian states. The usual figures I see quoted are that 50% of Indian Americans are Gujarati, 25% Punjabi, with the balance a host of other groups (e.g., Bengalis, Tamils, Assamese, etc.). Digging around, I found these data:
In 2006, 26.3 percent of Indian immigrants age 5 and older reported speaking Hindi at home. Gujarathi (14.1 percent) was the next most popular language, followed by English (10.1 percent), Panjabi (10.0 percent), Telugu (9.7 percent), Tamil (6.7 percent), Malayalam (6.1 percent), Urdu (3.4 percent), Marathi (3.1 percent), Bengali (2.2 percent), and Kannada (1.7 percent).