CREATE TABLE table_59553 ("Rider" TEXT, "Bike" TEXT, "Laps" FLOAT, "Time" TEXT, "Grid" FLOAT)

What is the sum of Grid, when Time is '+16.687'?
SELECT SUM("Grid") FROM table_59553 WHERE "Time" = '+16.687'
SELECT SUM("Grid") FROM "table_59553" WHERE "Time" = '+16.687'