1648 out of 2823 = 58% of  "How" questions are "How ADJ ..." 
       about the extent of something.  The remainder are more procedural:


1147 How many
 467 How do
 192 How can
 159 How does
 156 How much
 146 How long
 130 How did
  86 How is
  64 How old
  38 How are
  27 How far
  23 How tall
  23 How fast
  21 How was
  15 How big
  12 How were
  10 How come
   9 How would
   9 How often
   8 How has
   7 How to
   6 How high
   4 How should
   4 How large
   4 How deep
   3 How you
   3 How thick
   3 How hot
   3 How and
   2 How wide
   2 How may
   2 How heavy
   2 How have
   1 How weak
   1 How the
   1 How sweet
   1 How successful
   1 How strong
   1 How soon
   1 How slowly
   1 How sharper
   1 How rich
   1 How powerful
   1 How loud
   1 How effective
   1 How could
   1 How common
   1 How close
   1 How bright
   1 How bad
   1 How accurate
   1 How about