user
Instruction
Answer the question based on the provided table.


Table
Table Title: George Bush Intercontinental Airport
Table Content:
| Rank | City | Passengers | Top Carriers |
| --- | --- | --- | --- |
| 1 | Los Angeles, CA | 700,000 | American, Spirit, United |
| 2 | Chicago, IL | 673,000 | American, Spirit, United |
| 3 | Denver, CO | 654,000 | Frontier, Spirit, United |
| 4 | San Francisco, CA | 492,000 | United |
| 5 | Dallas/Fort Worth, TX | 488,000 | American, United |
| 6 | Newark, NJ | 480,000 | United |
| 7 | Las Vegas, NV | 442,000 | Spirit, United |
| 8 | Charlotte, NC | 441,000 | United, US Airways |
| 9 | Atlanta, GA | 400,000 | Delta, United |
| 10 | Phoenix, AZ | 393,000 | United, US Airways |


Question
how many domestic routes out of houston intercontinental have united as a carrier?


Answer Format
The final answer should be concise and use the following format:
```json
{
    "answer": [
        "answer1",
        "answer2",
        ...
    ]
}
```
rule
["10"]