Consider the following statements regarding Punjab’s declining own-tax revenue:

1. The introduction of GST has significantly improved Punjab’s own tax revenue.
2. The non-tax revenue-to-GSDP ratio has declined from 5% in 2001-02 to less than 1% in 2022-23.
3. The highest share of own tax revenue in Punjab comes from excise duty and GST.
4. Punjab’s land revenue has more than doubled between 2021-22 and 2022-23.

Which of the above statements are correct?