Phrasing the question in terms of "freedom from Pakistan" is clearly biased towards India. Full independence (from both Pakistan and India) is the most popular option across Kashmir as a whole, but even that is not supported by a majority.
A deleted answer originally posted by user17569 cites the Chatham House survey published in 2010. This apparently remains the most systematic and independent attempt to measure public opinion on the issue within Kashmir. It looks in detail at different questions and compares the different provinces. Here is a summary of the key results:
The two questions envisaged under the UN resolutions of 1948/49, which proposed a plebiscite, were
restricted to the choice of the whole of the former Princely State of Jammu and Kashmir joining India
or joining Pakistan. This poll shows that preference for those options is highly polarized. 21% of the
population said they would vote for the whole of Kashmir to join India, and 15% said they would vote
for it to join Pakistan. [...]
The option of independence has been widely promoted on both sides of the LoC over the last twenty
years. However, although 43% of the total population said they would vote for independence, in only five
out of eighteen districts was there a majority preference for the independence of the whole of Kashmir.
Note that in these results, those who support joining India (21%) and those who support independence (43%) total just under 2/3 of the population (64%). The 73% result is probably consistent with this, considering the loaded wording of the question in terms of "freedom from Pakistan", as only 15% said they want to join with Pakistan.
