New Super Mario Bros. was released by Nintendo in North America on May 15, 2006, in Japan on May 25, 2006, in Australia on June 8, 2006, and in Europe on June 30, 2006.[35] Nintendo did not specify why it chose to delay the game's release in its home market of Japan by ten days, but GameSpot noted that "it stands to reason that the company simply wants a few more days to build inventory."[36] It was given generally favorable reviews, receiving an aggregated score of 89% from Metacritic.[19] Praise focused on improvements made to the Mario franchise, while criticism targeted the game's simplicity. In Japan, over 480,000 units of New Super Mario Bros. were sold on the day it was released and 900,000 copies in the first four days.[37] At the time, it was the best-selling debut for a Nintendo DS game in Japan,[37] but it has since been surpassed by Pokémon Diamond and Pearl.[38] It is Japan's 26th best-selling game in 2008.[39] In the United States, 500,000 copies of New Super Mario Bros. were sold in the first 35 days,[40] and one million copies were sold twelve weeks after its release.[41] It was the 12th best-selling game and the second best-selling Nintendo DS game of December 2008 in the United States.[42] Worldwide,five million copies were sold as of April 2008,[43] and over eighteen million as of March 2009.[44] As of March 31, 2013, the game's worldwide sales have reached 30.38 million.[45]