Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Rnd | Date | Length | Race Name | Track | Location | Pole Position | Winning Driver |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1.0 | March 18 | Jimmy Bryan 150 | mi (km) | Phoenix International Raceway | Avondale , Arizona | Bobby Unser | Bobby Unser |
| 2.0 | April 23 | Trentonian 200 | mi (km) | Trenton International Speedway | Trenton , New Jersey | Bobby Unser | Gary Bettenhausen |
| 3.0 | May 27 | International 500 Mile Sweepstakes | mi (km) | Indianapolis Motor Speedway | Speedway , Indiana | Bobby Unser | Mark Donohue |
| 4.0 | June 4 | Rex Mays Classic | mi (km) | Wisconsin State Fair Park Speedway | West Allis , Wisconsin | Bobby Unser | Bobby Unser |
| 5.0 | July 16 | Michigan 200 | mi (km) | Michigan International Speedway | Brooklyn , Michigan | Bobby Unser | Joe Leonard |
| 6.0 | July 29 | Schaefer 500 | mi (km) | Pocono International Raceway | Long Pond , Pennsylvania | Bobby Unser | Joe Leonard |
| 7.0 | August 13 | Tony Bettenhausen 200 | mi (km) | Wisconsin State Fair Park Speedway | West Allis , Wisconsin | Mario Andretti | Joe Leonard |
| 8.0 | September 3 | California 500 | mi (km) | Ontario Motor Speedway | Ontario , California | Jerry Grant | Roger McCluskey |
| 9.0 | September 24 | Trenton 300 | mi (km) | Trenton International Speedway | Trenton , New Jersey | Bobby Unser | Bobby Unser |
Question:
What rounds did Phoenix International Raceway host?
Answer:
1.0