st: standard normal distribution

[tashi lama <ltashi32@hotmail.com>]

Hello all, 
   This might be more of a statistical question than stata but I would really appreciate if someone explain me this. I thought I understood normal distribution until I see this. I have a standard normal distribution table with N(mean=0,standard deviation=1) which gives me the following 

      x          y 
  |---------------|
  | -9   1.03e-18 |
  | -8   5.05e-15 |
  | -7   9.14e-12 |
  | -6   6.08e-09 |
  | -5   1.49e-06 |
  |---------------|
  | -4   .0001339 |
  | -3    .004433 |
  | -2   .0540047 |
  | -1   .2420321 |
  |  0   .3990434 |
  |---------------|
  |  1   .2420321 |
  |  2   .0540047 |
  |  3    .004433 |
  |  4   .0001339 |
  |  5   1.49e-06 |
  |---------------|
  |  6   6.08e-09 |
  |  7   9.14e-12 |
  |  8   5.05e-15 |
  |  9   1.03e-18 |
  | 10   7.70e-23 |
  +---------------+

summ y 
Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
           y |        20    .0500127    .1105588   7.70e-23   .3990434

Do I not must get mean of  y to be 0 and standard deviation to be 1 since it is a normal distribution N(0,1). Am I misunderstanding something here??

Thanks, 
Tashi  		 	   		  
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