I assume this is only employment green cards. Most Mexican Americans probably come in on family based green cards, or just got citizenship by birth in the US.
Even China has only 45K greencards. They seem to follow the same pattern as India for immigration, so what category are they coming in. Last I checked both countries (India, China) have similar number of immigrants in the US.
I don't know, but the EB2 and EB3 backlogs for India are longer than for China so there must be some difference.
Assuming those numbers are from PERM applications though, they don't correspond one-to-one to immigrants. For example Indians have a multi year wait to get a green card after their PERM is approved, and anytime they change employers while waiting they will likely apply for a new PERM, so by the time they get their green card one Indian could have gone through many PERM approvals (which this website will probably count separately).
