| Schedule of quarterly financial information | 
Our quarterly results of operations are summarized below: 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|   | For the Three Months Ended |  
|   | March 31 |   | June 30 |   | September 30 |   | December 31 |  
| 2018 |   |   |   |   |   |   |   |  
| Total revenue | $ | 1,375,102 | 
 |   | $ | 1,432,299 | 
 |   | $ | 1,467,383 | 
 |   | $ | 1,495,908 | 
 |  
| Cost of services | $ | (534,652 | ) |   | $ | (636,668 | ) |   | $ | (564,735 | ) |   | $ | (572,551 | ) |  
| Income from operations | $ | 423,591 | 
 |   | $ | 361,627 | 
 |   | $ | 482,557 | 
 |   | $ | 459,173 | 
 |  
| Net income | $ | 289,441 | 
 |   | $ | 292,352 | 
 |   | $ | 343,048 | 
 |   | $ | 251,052 | 
 |  
| 
Net income per common share--basic (1)
 | $ | 0.06 | 
 |   | $ | 0.07 | 
 |   | $ | 0.08 | 
 |   | $ | 0.06 | 
 |  
| 
Net income per common share--diluted (1)
 | $ | 0.06 | 
 |   | $ | 0.06 | 
 |   | $ | 0.07 | 
 |   | $ | 0.06 | 
 |  
| 2017 |   |   |   |   |   |   |   |  
| Total revenue | $ | 1,294,066 | 
 |   | $ | 1,347,569 | 
 |   | $ | 1,379,596 | 
 |   | $ | 1,403,898 | 
 |  
| Cost of services | $ | (497,107 | ) |   | $ | (513,446 | ) |   | $ | (519,024 | ) |   | $ | (572,405 | ) |  
| Income from operations | $ | 393,840 | 
 |   | $ | 416,353 | 
 |   | $ | 433,965 | 
 |   | $ | 396,706 | 
 |  
| Net income (loss) | $ | 207,073 | 
 |   | $ | 202,109 | 
 |   | $ | 275,722 | 
 |   | $ | (36,996 | ) |  
| 
Net income (loss) per common share--basic (1)
 | $ | 0.04 | 
 |   | $ | 0.04 | 
 |   | $ | 0.06 | 
 |   | $ | (0.01 | ) |  
| 
Net income (loss) per common share--diluted (1)
 | $ | 0.04 | 
 |   | $ | 0.04 | 
 |   | $ | 0.06 | 
 |   | $ | (0.01 | ) | 
 
|  |  |  
| (1) | The sum of quarterly net income per share applicable to common stockholders does not necessarily agree to the net income per share for the year due to rounding. |  |