Grand Prix Winners together on the F1 grid

[Supersam83]

Lando has become the newest first time F1 Grand Prix winner with his win in Miami.

At the next Grand Prix in Imola, there will be a total of 12 Grand Prix winners on the grid together.

12 drivers out of 20 is 60% which I believe is quite high.

Is this the highest number of Grand Prix winners on the grid competing at the same time?

[Supersam83]

List of the 12 F1 GP winners on the grid:

Max Verstappen
Sergio Perez
Lewis Hamilton
George Russell
Charles Leclerc
Carlos Sainz Jr
Pierre Gasly
Esteban Ocon
Fernando Alonso
Valtteri Bottas
Daniel Riccardo
Lando Norris

Only the Haas and Williams teams have drivers who haven't won an F1 GP race.