Show days of single week
Three minor notes:


From Steve McConnell, Code Complete 2nd Edition, 31.2 Layout Techniques, p737:


  Using blank lines is a way to indicate how a program is organized. You can use them
  to divide groups of related statements into paragraphs, to separate routines from one
  another, and to highlight comments.


It does not make sense if all groups contain only one line.
strtotime($year.'-W'.$week.'-'.$i) is used and duplicated multiple times in the code. You could extract it out to a function to remove the duplication.
If I'm right you are iterating through the days of the week with this loop:


&lt;?php for($i = 1; $i &lt;= 7; $i++): ?&gt;



Renaming $i to $weekday or something similar would make it obvious and help readers/maintainers a lot.