Look very consistent, which is good. However, it does show that the two pulses per revolution are slightly different lengths, so it will be important to always measure the pulses in pairs and use the total of the two answers.
Are all your fans identical? Try one or two more to see if there is much difference in the readings, using that sketch.
The total of a pair of readings comes to around 14,000us (I'll leave you to do a more accurate calculation) and this corresponds to 2200rpm. So to translate any pulse reading into rpm, multiply 2200 × 14000 and divide by the pulse reading. For example if a pair of pulse readings comes to 28000, rpm would be 2200×14000/28000 = 1100.