Hindu extremists claim that hindu population in pakistan decreased from 30% in post partition days to 3% today. They take it as an genuine reason to access license to spread hatred against muslims and kill them. Lets analyse this issue step by step and find out the truth:
The Hindu population in West Pakistan, that is today Pakistan, was 20% in 1941. That came down to 1.5% in 1951
According to the 1951 census, the population of west Pakistan was 33,816,000 or better 33.8 million
Around 6.5 million Muslims came into Pakistan while 5.4 Hindus left it. Therefore there was an addition of approximately 6.5-1.1=1.1 million people in the Pakistan population so we can assume that before the partition it was 33.8-1.1= 32.7 million.
http://ksghome.harvard.edu/~akhwaja/papers/The%20Big%20March%20December%202005.pdf(Look through Page 8 of the above pdf link)
Assuming the percentage of Hindus continued to remain 20% till 1947, their numbers before partition would have been 20/100 * 32.7= 6.54 million Hindus.Since we have established that 5.4 million Hindus left during the partition. 6.54-5.4=1.14 million Hindus were left behind. Using the same PDF link, we can estimate that around half a million Hindus were killed during parition riots therefore the net population of Hindus would have been 1.14-0.50= 0.64 million.So basically the percentage they now formed was 0.64/33.8 * 100= 1.89%
So the truth is, inspite of continous migration of pakistani hindus to dubai and other arab countries, their number has actual raised from 1.89% to 3%.