A study found that in a random sample of 200 high school cafeterias, 71% of them serve pizza daily. In a random sample of 2000 college or university cafeterias, 92% of them serve pizza daily. The researchers want to find 99% confidence interval for the difference between the proportion of high school cafeterias that serve pizza daily, and the proportion of college/ university cafeterias that serve pizza daily. What is the point estimate in this situation? (assume the sampling distribution)