 Complete the following phrase:  In 1969, the Belgian Grand Prix was boycotted by the F1 drivers because of the extreme danger of Spa. There had been ten car racing fatalities in total at the track in the 1960s, including five in the two years previous. The drivers demanded changes made to Spa which were not possible on short notice, so the Belgian Grand Prix was dropped that year. Armco barriers were added to the track and sections of it were improved especially the Stavelot and Holowell sections, just like they had been added for the 1969 Le Mans race. One last race there 