As per contract, India produces 51% of the MKI by value and over 75% by component. Only the landing gear and some engine parts are imported. The landing gear was originally planned to be indigenized, but was later imported due to its lower cost.
Such data is constantly released during interviews. So India releases information like the Russians do.
This is from 2014.
www.ajaishukla.com
Of the 43,000 components that go into a Su-30MKI, 31,500 components --- or 73 per cent --- are now being built in India.
Further indigenisation is blocked since the Indo-Russian contract mandates that all raw materials that goes into the Su-30MKI --- including 5,800 titanium blocks and forgings, aluminium and steel plates, etc --- must be sourced from Russia. The contract also stipulates that another 7,146 items like nuts, bolts, screws and rivets must be sourced from Russia.
HAL has also partially indigenised the Su-30MKI’s giant AL-31FP engines, which are built in Koraput, Odisha. 53 per cent of the engine by cost has been indigenised, with the remaining 47 per cent consisting of high-tech composites and special alloys --- proprietary secrets that Russia will not part with. Even so, HAL builds 87.7 per cent of the engine’s components in India.
Also I was wrong about 76%, that's for the airframe. Engine is 87.7%. The remaining 12.3% consists of the most expensive parts. A DRDO official had once pointed out that it was over 85%.
These limits are only for production of the jets, not the spare parts, as per the contract.
In any case, India is pushing for full indigenization of systems like tanks and aircraft, away from Russian influence. For example, the T-90 is getting a new Indian designed engine.
Anyway, if you read that India produced 60% of the MKI, then you just read old data. Indigenization percentage increased in a phased manner.