delay() is nearly never a solution (it is deprecated in 2.0).
See the Technical FAQ articles for an explanation why.

As phi.lho said, delay() is the wrong way to do this.  One way is to use the millis() function to work out how long has passed since the sketch started running and then draw an appropriate number points based on that.  This should help get you started:

1. int[] dataPoints;
2. 
   
3. void setup() {
4.   // Store the data points in a global array;
5.   dataPoints = new int[] {0, 10, 20, 35, 45, 32, 14, 58};
6.  
7.   size(640, 600);
8.   stroke(255);
9. }
10. 
    
11. void draw() {
12.   background(51);
13.  
14.   // work out how many points to draw based on the time passed
15.   int endPoint;
16.   int timeInterval = 2000;
17.   endPoint = floor(millis() / timeInterval);
18.  
19.   // can't draw beyond the number of points available
20.   if (endPoint > dataPoints.length - 1) {
21.     endPoint = dataPoints.length - 1;
22.   }
23.  
24.   // draw the appropriate number of points
25.   for (int i = 1; i <= endPoint; i++) {
26.     line(i * 10, dataPoints[i - 1], (i + 1) * 10, dataPoints[i]);
27.   }
28. }