Table:
text: United States House of Representatives elections, 1998
Pennsylvania
Pennsylvania
District Incumbent Party First_elected Results Candidates
Pennsylvania 15 Paul McHale Democratic 1992 Retired Republican gain Pat Toomey (R) 55% Roy Afflerbach (D) 45%
Pennsylvania 16 Joe Pitts Republican 1996 Re-elected Joe Pitts (R) 71% Robert Yorczyk (D) 29%
Pennsylvania 17 George Gekas Republican 1982 Re-elected George Gekas (R) unopposed
Pennsylvania 18 Mike Doyle Democratic 1994 Re-elected Mike Doyle (D) 68% Dick Walker (R) 32%
Pennsylvania 19 Bill Goodling Republican 1974 Re-elected Bill Goodling (R) 68% Linda Ropp (D) 29%
Pennsylvania 20 Frank Mascara Democratic 1994 Re-elected Frank Mascara (D) unopposed

Question: How many candidates ran in the 1998 United States House of Representatives election in Pennsylvania, where Mike Doyle was the incumbent?