I did my best, I have no regrets!
Books have more to compete with than ever before. Books used to be the only form of entertainment media around. Then we got music players. Then we got radio. Then we got television. Then we got video games. Then we got the internet. It would be impossible for books to not decline in popularity.It's not clear from the cited links, but I wonder if it's because as the population is growing, the growth rate of nonreaders (by which I mean people who choose not to read, not those who can't) is higher than the readers.
So it's not that people are giving up reading (i.e. number of readers is decreasing), or that each person who dies is being replaced by a nonreader so eventually we'll have no readers. Each year still gives us more readers than are dying, but we're also getting a lot more nonreaders in addition, so the percentage drops even as the numbers increase.
Now, with the internet, we also have access to all of the above in a more convenient format. Books have been losing popularity because we only have so many hours to devote to leisure activities, but an increasing amount of items competing for those hours. I read a lot less these days than when I was younger. Much of it is because I have very little time and video games + television + internet usually eats up those hours. I don't even have time for film and I usually have to double task on the music while on the bus/train and play a handheld game.
Although I did just get a delivery of close to 40 volumes of One Piece which I went through in less than a month >.> Might pick up another book soon. I forgot how much I enjoyed reading.
Oh, by the way:
Sales for Harry Potter and the Deathly Hallows were record setting. The initial U.S. print run for Deathly Hallows was 12 million copies, and more than a million were pre-ordered through Amazon and Barnes & Noble. On 12 April 2007, Barnes & Noble declared that Deathly Hallows had broken its pre-order record, with more than 500,000 copies pre-ordered through its site. On opening day, a record 8.3 million copies were sold in the United States, and 2.65 million copies in the United Kingdom. At WH Smith, sales reportedly reached a rate of 15 books sold per second. By June 2008, nearly a year after it was published, worldwide sales were reportedly around 44 million.