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:
| Team | Truck(s) | # | Driver(s) | Primary Sponsor(s) | Listed Owner(s) | Crew Chief |
| --- | --- | --- | --- | --- | --- | --- |
| Addington Racing | Chevrolet Silverado | 60 | Travis Kvapil | CAT Rental Stores | Mike Addington | Rick Ren |
| Bobby Hamilton Racing | Dodge Ram | 4 | Brian Rose | Perry Connection | Debbie Hamilton | Danny Rollins |
| Bobby Hamilton Racing | Dodge Ram | 8 | Bill Lester (R) | Dodge Dealers | Bobby Hamilton | Kip McCord |
| Bobby Hamilton Racing | Dodge Ram | 18 | Robert Pressley | n/a | Bobby Hamilton | Danny Gill |
| Circle Bar Racing | Ford F-150 | 14 | Rick Crawford | Circle Bar Motel & RV Park | Tom Mitchell | Ray Stonkus |
| Countryman Motorsports | Ford F-150 | 15 | Rich Bickle | Dickies | Billy Ballew | Craig Osbourne |
| Green Light Racing | Chevrolet Silverado | 07 | Jason Small (R) | Sunbelt Rentals | Gene Christensen | Dennis Fiebel |
| Green Light Racing | Chevrolet Silverado | 08 | Bobby Dotter | People Against Drugs | Gene Christensen | Doug Howe |
| Joe Gibbs Racing | Chevrolet Silverado | 20 | Coy Gibbs | MBNA | Joe Gibbs | Doug Hewitt |
| K Automotive Racing | Ford F-150 | 29 | Terry Cook | Power Stroke Diesel | Kay Keselowski | Bob Keselowski |
| L&R Racing | Chevrolet Silverado | 90 | Lance Norick | Express Personnel Services | Ron Norick | Gary Showalter |
| MacDonald Motorsports | Chevrolet Silverado | 72 | Randy MacDonald | Greenfield Truck Center | Marrill MacDonald | Steve Bird |
| Morgan-Dollar Motorsports | Chevrolet Silverado | 46 | Dennis Setzer | Acxiom/Computer Associates | David Dollar | John Monsam |
| Orleans Racing | Dodge Ram | 62 | Brendan Gaughan (R) | NAPA Auto Parts | Michael Gaughan | Shane Wilson |
| Petty Enterprises | Dodge Ram | 43 | Carlos Contreras | Hot Wheels | Richard Petty | Howard Comstock |
| Portenga Motorsports | Chevrolet Silverado | 39 | Steve Portenga | Roto-rooter | Steve Portenga | George Church |
| Powers Motorsports | Dodge Ram | 55 | Tom Powers | University of Northwestern Ohio | Sherri Powers | Bryan Berry |
| R&J Racing | Dodge Ram | 68 | Rodney Sawyers (R) | n/a | Wendy Sawyers | Jeff Sawyers |
| RDS Motorsports | Dodge Ram | 79 | Jerry Hill | RDS Racing Engines | R. D. Smith | Ralph Wingfield Jr. |
| Roush Racing | Ford F-150 | 50 | Jon Wood | Navy Racing | Jack Roush | Dan Binks |
| SealMaster Racing | Chevrolet Silverado | 88 | Matt Crafton | Sealmaster | Duke Thorson | Jerry Cook |
| Shepherd Racing | Ford F-150 | 21 | Morgan Shepherd | n/a | Cindy Shepherd | Ted Jackson |
| Spears Motorsports | Chevrolet Silverado | 75 | David Starr | Spears Manufacturing | Wayne Spears | Dave McCarty |
| Tagsby Racing | Chevrolet Silverado | 73 | Loni Richardson (R) | Intensitee/UTI | Joey Sonntag | Joey Sonntag |
| Team Racing | Chevrolet Silverado | 86 | Dana White (R) | Red Line Oil/Coverall Carports | Phil Bonifield | Bernie Taft |
| Troxell Racing | Chevrolet Silverado | 93 | Jerry Allec, Jr. | n/a | Lonnie Troxell | Lonnie Troxell |
| Ultra Motorsports | Dodge Ram | 1 | Ted Musgrave | Mopar | Jim Smith | Gene Nead |
| Ultra Motorsports | Dodge Ram | 2 | Jason Leffler | Team ASE Racing | Marlene Smith | Tim Kohuth |
| Ware Racing Enterprises | Dodge Ram | 5 | Lance Hooper | Diamond Cut Jeans/Blair5.com | Rick Ware | Cal Northrop |
| Ware Racing Enterprises | Dodge Ram | 51 | Michael Dokken | OOIDA | Rick Ware | Ken Glen |
| Ware Racing Enterprises | Dodge Ram | 81 | Angie Wilson (R) | TotalRaceBabe.com | Rick Ware | Calvin Humphries |
| Xpress Motorsports | Chevrolet Silverado | 16 | Mike Bliss | IWX Motor Freight/Knights Inn | Steve Coulter | Travis Holt |
Question:
how many people are not driving a chevrolet silverado?
Answer:
18