Dear Natasha,

The were around 5500 seats in NEET 2017 second round counselling. For more information, you can go through the below mentioned sites.

https://indianexpress.com/article/education/neet-2017-over-5500-seats-vacant-supreme-court-extends-deadline-for-final-round-counselling/

https://medicine.careers360.com/news/neet-2017-aiq-second-round-seat-allotment-list-released-reporting-allowed-till-august-16-322655

Hope it helps.

Good Luck.