Solve the following math problem efficiently and clearly:

- For simple problems (2 steps or fewer):
Provide a concise solution with minimal explanation.

- For complex problems (3 steps or more):
Use this step-by-step format:

## Step 1: [Concise description]
[Brief explanation and calculations]

## Step 2: [Concise description]
[Brief explanation and calculations]

...

Regardless of the approach, always conclude with:

Therefore, the final answer is: $oxed{answer}$. I hope it is correct.

Where [answer] is just the final number or expression that solves the problem.

Problem: A 2 by 2003 rectangle consists of unit squares as shown below.  The middle unit square of each row is shaded.  If a rectangle from the figure is chosen at random, what is the probability that the rectangle does not include a shaded square?  Express your answer as a common fraction. [asy]
size(7cm);
defaultpen(linewidth(0.7));
dotfactor=4;
int i,j;

fill((6,0)--(7,0)--(7,2)--(6,2)--cycle,gray);

for(i=0;i<=3;++i)

{

draw((i,0)--(i,2));

draw((i+5,0)--(i+5,2));

draw((i+10,0)--(i+10,2));

}
for(j=0;j<=2;++j)

{

draw((0,j)--(3.3,j));

draw((0,j)--(3.3,j));

draw((4.7,j)--(8.3,j));

draw((4.7,j)--(8.3,j));

draw((9.7,j)--(13,j));

draw((9.7,j)--(13,j));

}

real x;

for(x=3.7;x<=4.3;x=x+0.3)

{

dot((x,0));

dot((x,2));

dot((x+5,0));

dot((x+5,2));

}[/asy]
user