Population growth and newspaper circulation are going in opposite directions. From Reflections of a Newsosaur:
Though circulation has fallen back to pre-Baby Boom levels, the population has more than doubled since 1946. If you divide circulation by population, you will find that fewer than 18 out of 100 Americans today buy a daily or Sunday newspaper. Back in 1946, 36% of the population bought a daily paper and 31% took a Sunday edition.