They published numbers for January - april.
http://news.xbox.com/2014/02/xbox-one-january-npd
http://news.xbox.com/2014/03/xbox-february-npd
http://news.xbox.com/2014/04/xbox-one-march-npd
http://news.xbox.com/2014/05/xbox-one-april-npd
After april I can not find any official MS reports on NPD numbers.
In 2013 they published NPD numbers most months.