It is estimate that the Pakistan's population will be over 180,000,000 by mid 2008. Pakistan had an estimated population of 169,300,000 as of July 2007,. During 1951-98, Pakistan's urban population expanded sevenfold. And by the next decade the population is expected to exceed 176 million. In the past, the country's population had a relatively high growth rate that has, however, been moderated by declining fertility and birth rates. Dramatic social changes have led to rapid urbanization and the emergence of megacities. During 1990-2003, Pakistan sustained its historical lead as the most urbanized nation in South Asia, with city dwellers making up 34% of its population.