Table:
text: Björn Borg career statistics
Singles: 19 finals (15 titles, 4 runners-up)
Singles: 19 finals (15 titles, 4 runners-up)
Outcome Year_ Championship Surface Opponent_in_the_final Score_in_the_final
Runner-up 1973 Monte-Carlo Clay Ilie Năstase 4–6, 1–6, 2–6
Runner-up 1973 Stockholm Hard Tom Gorman 3–6, 6–4, 6–7
Winner 1974 Rome Clay Ilie Năstase 6–3, 6–4, 6–2
Winner 1974 Boston Clay Tom Okker 7–6, 6–1, 6–1
Winner 1975 Boston Clay Guillermo Vilas 6–3, 6–4, 6–2
Winner 1976 Boston Clay Harold Solomon 6–7, 6–4, 6–1, 6–2
Runner-up 1976 Philadelphia Carpet Jimmy Connors 6–7, 4–6, 0–6
Winner 1977 Monte Carlo Clay Corrado Barazzutti 6–3, 7–5, 6–0
Winner 1977 London Carpet John Lloyd 6–4, 6–4, 6–3
Winner 1978 Tokyo Carpet Brian Teacher 6–3, 6–4

Question: Name the surface for Philadelphia under Bjorn Borg's singles: 19 playoffs (15 titles, 4 runners-up) career stats ?